Abstract: A method to measure the spacesuit joints' mechanical characteristics based on passive robot is given in this paper. Based on its special mechanical structure, a kinematic model of the IVA (intra-vehicular activity) spacesuit's arm is built. The inverse kinematics of spacesuit's arm based on artificial neural networks is put forward, and the constructional algorithm of the network architecture based on the generalization ability is developed. The joints' mechanical characterstics of an actual IVA spacesuit's arm is measured. Experimental results prove the effectiveness of the measuring principle and the proposed algorithm.