A low-cost three-dimensional coordinate measuring method based on ultrasonic sensors is proposed.One ultrasonic wave transmitting terminal and multiple ultrasonic wave receiving terminal are used in this method.The distances between transmitting and receiving terminal are calculated by the principle of ultrasonic ranging

then spatial three-dimensional coordinates of receiving terminal are calculated.On the basis of ultrasonic wave three-dimensional measurement method

three-dimensional position inversion algorithm based on least-square method is derived and measuring system based on FPGA is set up and experimental research is carried out.The experimental results indicate that the absolute error of coordinate estimation is less than 20 mm with good repeatability and measuring precision can be improved further.