In order to improve the processing accuracy of free bending forming technology for tubes, the precise prediction work was conducted on the forming parameters for the processing accuracy of planar bending tubes, and the experimental values of bending radius and bending angle were consistent with the designed values by establishing the prediction model of forming parameters. Firstly, the finite element simulation model was established and modified by tube processing experiments, and the optimized simulation model was used to establish the predicted sample database. Then, taking the bending radius and bending angle obtained by finite element simulation as input, and the designed values of bending radius and bending angle as output, combined with BP neural network and grey wolf optimizer algorithm, the forming parameter prediction model was built. The results show that the improved PGWO-BP neural network predicts the bending radius and bending angle with the maximum error of no more than 2%. At the same time, the prediction model is used to develop the process parameter determination software of tube precision forming.