In order to measure the pressure in the ultra-low temperature condition, the structure of ultra-low temperature piezoresistive pressure sensor is designed. Polysilicon nanometer thin film is used as a varistor according to its temperature and piezoresistive characteristics. The effect of the dimensions of silicon elastic membrane for the sensor sensitivity and the strain dimensions of the elastic membrane are analyzed, then layout position of resistances is arranged. The package structure of pressure sensor is designed. Meanwhile, a low-temperature sensor is designed to compensate the temperature influence to the pressure sensor.