Abstract: For limitations that monitoring signal of coal piling sensor based on limit switch is inaccurate and action point (inclination angle) of coal piling sensor based on mercury switch ca't be set flexibly, the paper put forward design scheme of a new mine-used coal piling sensor based on ADXL335 tri-axial accelerometer and introduced main circuits design of the sensor. The sensor used measurement function of tri-axial angle of accelerometer to make comprehensive high precision measurement, and can transmit signal to protection control system of belt conveyor to prevent continuous accumulation of coal timely and accurately.