The invention discloses a DICOM planning file compatibility conversion system and method. The compatibility conversion method includes a leading-in step, a visual display step, a data conversion step and a lead-out step; in the leading-in step, a DICOM planning file is led in, and image and parameter information in the planning file is analyzed; in the visual display step, the image and parameter information of the planning file is displayed on a system interface; in the data conversion step, the name and machine parameter of a target planning system for compatibility conversion are set, and data conversion is conducted on the image and parameter information of the planning file; in the lead-out step, the image and parameter information obtained after data conversion is re-wrote in the DICOM planning file and stored at a target position or transmitted the target planning system through the network. The system and the method can solve the incompatible problem of DICOM planning file transmission, so that patient plans can be implemented quickly and efficiently.