In this paper,we discuss how the multi-reflection of thermal emission affects the calculation of radiation balance.With the help of computer graphics,the four components of discrete vegetation are analyzed in detail and the curves of BRDF for the discrete vegetation can be obtained as well.A new model is put forward to inverse the temperatures of four components.The solution obtained by using computer graphics is consistent with observations in the field experiment in Yucheng Remote Sensing Comprehensive Site of CAS.Furthermore,the method can be used to retrieve land surface temperature based on multi-angle thermal infrared remotely sensed data.