Abstract: With the development of linear transformer driver, the number of gas switches in the driver increases rapidly, and thus multi-output synchronization trigger has become one of the key technical obstacles. The paper summarizes the recent researches about electical pulse trigger, laser trigger and trigger based on photo-conductive semiconductor switches. Characteristics and trigger requirements of multi-channel multi-gas switches are reported. Developments in key technologies of trigger system are analyzed. The crucial technique problems that should be investigated in the future and some research approaches are presented.