Abstract: A new evaluating model was introduced and a new target function was defined. The plant growth simulation algorithm (PGSA) solving the target function was improved. The related codes were written in C++ and CUDA, and were accelerated by GPU. Two big facilities from different cooperative companies were rearranged individually and their new dose field distributions were also detected individually by different potassium dichromate dosimeters. The results show that the experimental dose unniformity (DUR) accords well with the theoretical ones, and the relative deviation is less than 4.125%. Compared with the old evaluation model, the DUR obtained by new model increases little, the energy efficiency is improved for several times, and the computation time is reduced from hours to minutes. The results verify the feasibility and validity of the new method.