For resolving rapid replacement of field replaceable module of artillery electrical control system under power on situation, put forward a method to realize hot swap circuit. Introduce work principle of hot swap technology, design signal hot swap circuit based on short post signal and power supply hot swap circuit based on LM5069 circuit, carry out power supply hot swap test and signal hot swap test separately. The simulation test result shows that: the hot swap circuit design is correct, it can be used in field replaceable module and it improves the reliability and rapid maintainability of the system effectively.