In order to provide the driving force for the collection and transport of the micro liquid in a microfluidic chip developed by our research group in earlier research, this paper presents a micro positive pressure generator based on the released gas by thermal decomposition of azobisisobutyronitrile (AIBN). The AIBN is fixed to a micro-heater and heated to 70 ℃ to produce a certain amount of positive pressure. Experimental measurements show that this micro positive pressure generator can obtain 182 kPa pressure with heating 8.7 mg of AIBN by a heating current of 900 mA. The designed micro positive pressure generator is a smaller size, pressure controllable and easy to produce, and obtained pressure can satisfy the requirements of transdermal interstitial fluid (ISF) extraction.