Lidar echo scene generation, based on three-dimensional scene construction and laser scattering principle, can be used to simulate the laser echo characteristics of real scenes and is an important means for testing the performance of laser array detector. To efficiently generate dynamic scene with high simulation accuracy, an adoption degree composed of the simulation similarity of laser echo scene and scene calculation time is constructed and used as the evaluation function. The spatial mesh number of laser echo scenes is thereby optimized. For an area array detector with 128×128 elements, the proposed method is used to optimize the number of spatial meshes of laser echos in two experimental scenes with different materials and distances. When subdivision number of the detector single pixel is 3×3 and the total number of spatial meshes is 384×384×L (L is subdivision number determined by distance accuracy), the adoption degree reaches the maximum values. The average generation time of each frame scene is less than 8 ms, and the dynamic scene generation with high frame rate (125 Hz) and high fidelity is realized. The theoretical and experimental results show that this method can balance the similarity of the generated echo scene and computing resource consumption when the computing resources are limited, and it is a practical optimization method for three-dimensional laser echo scene generation.