Pre-release 20 kJ energy system provides pump pulse for the rod xenon lamp of laser pre-amplifier, which is an important part of SG-Ⅲ host high power solid laser device. The stability of pre-placed 20 kJ system energy trigger discharge seriously restricts the debugging efficiency of pre-placed system and the formal laser targeting efficiency. The situations of early discharge, non-synchronous discharge and not discharge are found during the joint debugging process of the pre-placed energy system and A1/A2/A3 beam group pre-placed system rod amplifier. The stability of pre-placed 20 kJ energy system trigger discharge is studied, and corresponding measures are put forward and tested, which can improve the trigger discharge stability of 20 kJ energy system significantly.