The pressure relief channel of high voltage（HV） switchgear is the key part to release overpressure caused by internal short-circuit explosion

and the safe and reliable action of it is the fundamental guarantee to ensure the safety of equipment

maintenance personnel and buildings. Taking a 7.2 kV HV switchgear as an example

we analyzed the shortcomings of the existing pressure relief channel

and put forward the improved design method of the pressure relief channel. Based on the NSGA-II（non-dominated sorting genetic algorithm-II）

and the SCM（standard calculation method） considering the pressure relief vent

the related parameters of the improved pressure relief channel were designed optimally. Then the optimal improvement project of the pressure relief channel was obtained. The results show that the deficiency of the existing pressure relief channel is made up effectively by adding the buffer chamber and arc guide channel at the top of the switchgear. After the pressure relief channel being improved

the average impulse and pressure peak of the switchgear door and partition are reduced obviously. The larger the size of pressure relief cover

the volume of buffer chamber and arc guidance channel

the better the effect of pressure relief. The proposed optimal design project of the pressure relief channel improves the safety and reliability of the switchgear. The results can be promoted to the HV switchgears in other voltages.