The invention discloses a collision-free path planning method for an industrial mechanical arm based on an A* algorithm. Firstly, parametric modeling is conducted on the six-degree-of-freedom mechanical arm, and a forward kinematic model of the mechanical arm is built; then, OBBs of the mechanical arm and the environment are constructed; the evaluation function and the search step size of the A* algorithm are set, and whether the mechanical arm collides with the environment or not is judged in each searched step through a collision detecting algorithm based on separating shafts; and finally, according to the principle that the sum of joint rotating angles is minimum and collision is avoided, searching is conducted in a six-dimensional joint space of the mechanical arm, and thus a collision-free path is obtained. The problem that aiming at the six-degree-of-freedom mechanical arm, searching cannot be conducted successfully through a traditional A* algorithm is solved, the searching efficiency of the algorithm is improved, and an effective method is provided for path planning of the industrial mechanical arm under the situation that obstacle distribution is known.