Aiming at the limitations of single pyroelectric infrared sensor(PIR) array in the target trajectory measurement, the method of using four PIR array sensing platforms to form the square perceptive model was put forward to measure the target trajectory. In this study, eight PIR probes were used to form M word array, with each probe evenly distributed at 45 degrees intervals. Four PIR array sensing platforms were arranged at the four vertices of the square model, and 32 senor angle data fusion through the adaptive weighted fusion algorithm of multi-sonsor data. At last, four sensing platforms used the coordinate and time information of the detected target to calculate the target′s motion trajectory and obtained the target′s speed. The experimental results show that this method can effectively make up for the deficiency of the function which can only realize positioning and low accuracy of single PIR array, and realize the accurate measurement of motion trajectory and the prediction of the target position in time sequence. So, this method has great theoretical significance and practical application value.