This topic takes the miniature Pt resistance strain pressure sensor made by Institute of Electronics, Chinese Academy of Sciences, as the core sensing element, and designs corresponding high-precision, low cost, low power amplifying circuit so as to realize accurate detection of atmospheric pressure in time. In this topic, a new design of amplifying circuit is taken, which first connects the digital potentiometer to the bridge circuit to adjust its balance, and then amplifies the output signal of the bridge circuit once to ideal value. This design not only meets the requirement of measurement, but also is feasible and reduces the cost. At the same time, in order to improve the precision of the potentiometer adjusting the bridge balancing, paralleled resistances are creatively used beside the digital potentiometer and its influence to the bridge balance adjustment and the accuracy of the bridge measurement is analyzed in detail.