Objective To investigate the probability of verifying the X-knife treatment plan by the radiotherapy simulator,and to analyze and report the errors of the X-knife treatment plan for reference.Methods The radiation fields of the X-knife treatment plan were observed in the whole simulating treatment process by the radiotherapy simulator.Results The error rate of X-knife treatment plan were in the simulating treatment process was 5.9%(22/372).Among the errors,3 cases of X-knife plans were found in the simulating treatment process,and the errors of isocenter in Z direction were 10cm.Conclusion This is a special error of X-knife TPS,which deserves more attention in stereotactic radiotherapy.