This paper has studied and designed a sensor for the A~2 (Automotive Applications).The sensor can measure the acceleration and deceleration of the automotive.In the event of a crash.the sensor supplies a controller with an electric signal.which corresponds to the progress of deceleration.The operationaI principle and behavior for the sensor system is discussed mainly in this paper. The paper has studied and designed a sensor for the A ~ 2 (Automotive Applications). The sensor can measure the acceleration and deceleration of the automotive. In the event of a crash. The sensor supplies a controller with an electric signal. Whi corresponds to the progress of deceleration. The operation of I principle and behavior for the sensor system is discussed mainly in this paper.