This article focuses on the prediction of forming trajectory and process optimization during the forming process for the variable curvature tubes. Firstly, through cubic B-spline interpolation, the geometric characteristics of the axis of the target tube are obtained. An overall tube is "separated and then integrated", and the relationship between geometric parameters and processing parameters is established to obtain the initial process parameters. Based on the Extended Kalman Filter (EKF) algorithm, the motion model and observation model of tube forming using simulation are presented section by section, and the relevant calculation and analysis are carried out. The forming trajectory has been predicted and the processing parameters are optimized during the processing process, in which the effectiveness of the processing optimum scheme is illustrated.