Three-dimensional laser scanning can collect point cloud information instantaneously and efficiently,and has unique advantages in obtaining plant phenotypic characteristics. The irregular geometric structure of the plant leads to its complex light radiation process. In this paper,dense spots of four representative plants were collected by laser scanner,and digitized as three-dimensional model to calculate structural phenotypic parameters accurately. By replacing the traditional empirical parameters of the SAIL model with the accurate leaf inclination angle distribution and leaf area index calculated by the laser point cloud,the intermediate parameters are reduced and the simulation accuracy is improved. And multi angle analysis,the simulated reflectance and measured reflectivity showed that simulation results have greatly improved in the direction of the main plane,vertical plane direction to improve the degree of vegetation is relatively weak;absorption valley,such as 450 nm,670 nm,has a strong anisotropic spectrum at the same time,the influence of structure parameters is also more prominent. The effect of improvement is obvious,while in the near infrared reflectance peaks such as 860 nm,it has no obvious improvement. In this paper,the feasibility of obtaining the plant phenotypic parameters by laser is proved,and the accurate structure parameters are successfully used to solve the difficult problems in the radiation transfer.