The invention discloses a temperature and pressure balancer used for a natural gas expansion process and an application thereof. The device is composed of a main tank body, a top end enclosure, a gas conducting system and a temperature returning system; the gas conducting system comprises a gas inlet pipe, a gas outlet pipe and a conical breaker; the temperature returning system comprises a baffle plate, silk screen padding and a rectangular fin. The device is used for the rear side of an expansion machine in the natural gas pipeline pressure energy expansion power generation flow to regulate the problems of over-low downstream natural gas temperature, discontinuous gas discharge and the like due to the natural gas flow rate change, expansion machine structure and the like. The temperature and pressure balancer used for the natural gas expansion process is featured with simple structure and convenience in mounting and suitable for solving the problems of unstable natural gas pressure, over-low temperature and the like in the natural gas pipeline pressure energy expansion power generation process.