Aiming at the low efficiency of the traditional constant arc?length method in solving nonlinear heat transfer problems, a self?developed improved arc?length method is adopted to study its application in nonlinear heat transfer analysis. The nonlinear intensity of the current incremental step is characterized by the 2?norm of the tangent increment in the prediction stage of adjacent incremental steps, and the arc?length calculation strategy is dynamically optimized to balance solution efficiency and numerical accuracy. Numerical simulations are conducted on three typical nonlinear heat transfer cases: material nonlinearity coupled with nonlinear surface heat flux, material nonlinearity coupled with nonlinear volume heat flux, and material nonlinearity coupled with thermal radiation. The results verify the feasibility and effectiveness of the improved arc?length method. The verification results show that under the scale of one million elements, the solution time of the improved method is reduced to about 50% of that of the traditional constant arc?length method, with the maximum relative error controlled within 5%. It provides a new technical approach for the efficient numerical solution of engineering nonlinear heat transfer problems.