Abstract: A finite element calculation model for the temperature field of medium-frequency induction heating postweld heat treatment has been established and experimentally validated. Using this model, the effects of heating rate on the isothermal holding time and axial temperature gradient during heat treatment were analyzed, and an optimization method for the heating rate in medium-frequency induction heating post-weld heat treatment was proposed. The results show that the model’s calculation results align well with the experimental results. Increasing the heating rate can enhance heat treatment efficiency but may result in insufficient constant temperature time on the inner wall. A higher heating rate can lead to a larger axial temperature gradient, which could compromise the safety of pipeline service. Based on the principle of controlling the axial temperature gradient, the maximum heating rate for different wall thickness pipelines was calculated using finite element calculations and least squares fitting methods. This study also provides a selection scheme for the maximum heating rate in medium-frequency induction heating post-weld heat treatment, which is suitable for engineering applications.