Mutual alignment accuracy is a main factor which affects the joint cal ibration of panoramic stereo cameras and laser radars in the dynamic spatial sensing area.To improve the result of joint calibration,we analyze the traditional technology of mutual alignment with telescope cross wire s.As it is tedious and difficult,a new method of mutual alignment based on four-quadrant detectors is provided.Th e laser transmitter,four-quadrant detector and coarse aiming device are respectively arranged on two instruments. And the laser beam irradiates the active area of four-quadrant detector through coarse aiming.Then the center of light spot offset relative to the center of the active area is obtained according to the output voltage of four quadrants.Thus the positions and the poses of two instruments can be adjusted properly to realize mutual alignment.The simulation analysis and experimental results indicate that the four-quadrant detector alignment accuracy can meet the requir ement of mutual alignment.This method provides a new idea for joint calibration,which operates more easily than the mu tual alignment technology based on the telescope cross wire.