For a cooperation imaging tracking system consisting of multiple moving platforms, time synchronization among these platforms was a critical demand. Based on the study of the hardware time model, the software Scheduling model, and data interaction & fusion process, a novel time synchronization method modified from RBS protocol was proposed. In the proposed method, firstly each platform used hardware to count the accurate sending period of the centre fusion node. Then the time error was extracted in each platform locally. Finally the extracted time error was used in the software time model to accomplish the time synchronization. The implementation structure and the precision of the proposed synchronization method were given in the paper.