In order to solve the forming problems such as difficult deformation and easy cracking of high strength steel square tubes, the local induction heating technology has been introduced based on the traditional cold forming process. An electromagnetic-temperature multi-field coupling model for local induction heating is established by using ANSYS parametric design language based on the magnetic vector potential and physical environment method. A numerical simulation is conducted at different heating process parameters, and the optimized parameters are used for experimental research. The simulation results show that the induction heating efficiency can be significantly improved by using magnetizers to increase the magnetic field intensity. As the heating frequency increase, the heating speed of the outer fillet area and the temperature difference between the outer and inner fillet area increase. As the heating power increases, the high temperature area and the peak temperature increase, but the outer fillet area is more prone to be overheated. The experimental results show that a high strength steel square tube with an extremely small fillet radius, increased corner thickness, but with no crack defect can be obtained by using the optimized heating process parameters. The average error between the simulated and measured heating temperature is about 7.57%, indicating that the finite element model has a good prediction accuracy.