Abstract: In order to enable the robot to adapt to the broader and more complex tasks and make human and robot achieve collaboration and communion, the accurate and real-time calculation of relative distance between the human and the robot becomes an unavoidable issue. For the problem, a modeling method of human-robot distance in collaboration environment and an iterative algorithm for computing the minimum distance between the human and the robot are presented. Firstly, the structure features of the robot are constructed by the 3D model of the robot, and human skeletal features are extracted by 3D visual sensor. The above two groups of features are mapped to the same coordinate space to establish the human-robot distance model in collaboration environment. Then, on the basis of this model, the minimum distance between the human and the robot is computed iteratively and the corresponding spatial position points are given. Finally, the YuMi robot of ABB company is used as the test object to measure the minimum distance between the human and the robot. The experimental results show that the proposed method reduces the difficulty of modeling and realizes the real-time calculation, and the validity and practicability of the proposed modeling method and iterative algorithm are verified.