Abstract: The double shell gas puff is applied extensively in Z pinch experiments because it can reduce R-T instability during the implosion phase. The design of the double shell gas puff was described, including the whole configuration, the synchronization of the gas release valves and the airproof of the inner and the outer chambers. The main factors which affect the airproof of the chambers were analyzed and the parameters of the springs were calculated. The gas release system consisting of the winding, iron core and the pull rod was also simulated, and the result proved that the system completely satisfied the demand of the Z pinch experiments. At last, the result of the testing experiment on ‘Qiangguang Ⅰ’ is given and it proves the practicality of the double shell gas puff.