Aiming at the shortcoming of current sensor calibration algorithm, introduce the integration extrinsic calibration algorithm of unmanned ground platform multi-sensor based on 3D calibration item. Based on research of foreign and demotic intelligence mobile robot sensor calibration, establish the unmanned ground platform and multi-sensor coordinate system. Introduce the multi-sensor extrinsic calibration method and its steps based on 3D calibration item, extrinsic calibration of multi-layer laser range finder and CCD camera, homogeneous transformation among coordinate system, and L-M nonlinear optimum algorithm. Carry out validation and error analysis of calibration. The method is successfully used in middle-size unmanned ground platform project. The application results show that the method can correct the installation position error of each sensor, and ensure the consistency of calibrated sensor measurement accuracy and object (obstacle) in platform coordinates system.