diff --git a/src/camera.rs b/src/camera.rs
index 904d12c..38b3426 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -12,6 +12,7 @@ impl Camera {
         camera_center: Point,
         focal_length: Vec3,
         sample_times: i8,
+        reflect_depth: i8
     ) -> Self {
         let image_height = ((image_width as f32 / aspect_ratio) as i32).max(1);
         let viewport_width = viewport_height * (image_width as f32 / image_height as f32);
@@ -45,7 +46,8 @@ impl Camera {
             viewport_u_delta,
             viewport_v_delta,
             viewport_top_left_pixel_center,
-            sample_times: sample_times,
+            sample_times,
+            reflect_depth,
         }
     }
 
@@ -67,7 +69,7 @@ impl Camera {
                         + (i as f32 + bias.x) * self.viewport_u_delta
                         + (j as f32 + bias.y) * self.viewport_v_delta;
                     let r = Ray::new(self.camera_center, pix_sample - self.camera_center);
-                    let sample_color = self.ray_color(&r, world);
+                    let sample_color = self.ray_color(&r, self.reflect_depth, world);
                     color = color + sample_color;
                 }
                 // color * each sample color
@@ -89,15 +91,21 @@ impl Camera {
         img_content
     }
 
-    fn ray_color(&self, ray: &Ray, world: &HittableList) -> Vec3 {
-        let hr = world.hit(&ray, 0.0, f32::MAX);
+    fn ray_color(&self, ray: &Ray, depth: i8, world: &HittableList) -> Vec3 {
+
+        // 反射次数
+        if depth <= 0 {
+            return Vec3::new(0.0, 0.0, 0.0);
+        }
+
+        // 限制出射光线的角度（0.001经验值）
+        let hr = world.hit(&ray, 0.01, f32::MAX);
         if hr.t >= 0.0 {
-            let normal_color = 0.5 * (hr.normal + Point::new(1.0, 1.0, 1.0));
-            return if hr.front_face {
-                normal_color
-            } else {
-                Color::new(1.0, 1.0, 1.0) - normal_color
-            };
+            // diffuse normal vec
+            let diffuse_vec = Vec3::random_unit();
+            let lambertian_vec = diffuse_vec + hr.normal;
+            // 每次反射按0.5计算颜色（反射率 ）
+            return 0.5 * self.ray_color(&Ray::new(ray.point, lambertian_vec), depth - 1, world);
         }
         // v / |v|
         let unit_direction = ray.direction / ray.direction.length();
diff --git a/src/main.rs b/src/main.rs
index 9451879..88871a3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -22,14 +22,17 @@ fn camera_render() {
         2.0,
         Point::new(0.0, 0.0, 0.0),
         Vec3::new(0.0, 0.0, -1.0),
-        10
+        100,
+        50
     );
     // world
     // world objects(spheres)
     let mut world = HittableList::new();
-    world.put(Box::new(Sphere::new(Point::new(0.0, 0.0, -1.0), 0.5)));
-    world.put(Box::new(Sphere::new(Point::new(0.1, -100.0, -0.0), 100.0)));
-    world.put(Box::new(Sphere::new(Point::new(-0.5, 0.2, -0.5), 0.2)));
+    world.put(Box::new(Sphere::new(Point::new(0.0, 0.1, -1.0), 0.5)));
+    world.put(Box::new(Sphere::new(Point::new(0.3, 0.1, -1.0), 0.1)));
+    world.put(Box::new(Sphere::new(Point::new(-0.5, 0.0, -1.0), 0.3)));
+    world.put(Box::new(Sphere::new(Point::new(0.0, -100.0, -1.0), 100.0)));
+    world.put(Box::new(Sphere::new(Point::new(-0.5, 0.2, -0.5), 0.4)));
 
     let ppm_content = camera.render(&world);
     write_image(
diff --git a/src/types_defined.rs b/src/types_defined.rs
index 4b5a4c6..01b784c 100644
--- a/src/types_defined.rs
+++ b/src/types_defined.rs
@@ -43,7 +43,8 @@ pub struct Camera {
     pub viewport_top_left_pixel_center: Vec3,
 
     // sample times
-    pub sample_times: i8
+    pub sample_times: i8,
+    pub reflect_depth: i8
 }
 
 /*
diff --git a/src/vec3.rs b/src/vec3.rs
index cc277df..6464960 100644
--- a/src/vec3.rs
+++ b/src/vec3.rs
@@ -1,6 +1,7 @@
 
 use std::{fmt::Display, ops::{Add, AddAssign, Div, Mul, MulAssign, Sub}};
 use std::fmt;
+use rand::{thread_rng, Rng};
 use crate::types_defined::Vec3;
 
 impl Display for Vec3 {
@@ -36,6 +37,33 @@ impl Vec3 {
         return self.length_squared().sqrt();
     }
 
+    pub fn random_range(min: f32, max: f32) -> Self {
+        let rng = &mut thread_rng();
+        Vec3::new(rng.gen_range(min..max), rng.gen_range(min..max), rng.gen_range(min..max))
+    }
+
+    pub fn random() -> Self {
+        let rng = &mut thread_rng();
+        Vec3::new(rng.r#gen(), rng.r#gen(), rng.r#gen())
+    }
+
+    pub fn random_unit() -> Self {
+        loop {
+            let v = Vec3::random();
+            if f32::MIN < v.length_squared() && v.length_squared() <= 1.0 {
+                return v / v.length_squared();
+            }
+        }
+    }
+
+    pub fn random_unit_on_hemisphere(point_normal: Vec3) -> Self {
+        let on_unit_sphere = Vec3::random_unit();
+        if on_unit_sphere.dot(point_normal) > 0.0 {
+            on_unit_sphere
+        } else {
+            Vec3::new(0.0, 0.0, 0.0) - on_unit_sphere
+        }
+    }
 }
 
 impl Add for Vec3 {