Series double-pass hot compression experiments were carried out on the MTS810-25T low-cycle fatigue testing machine for the new type alloy of high-quality GH738. The effects of initial grain size, deformation temperature, holding time between passes and strain rate on the evolution of sub-dynamic recrystallization structure of high-quality GH738 alloy were analyzed. Furthermore, combined with quantitative metallography and nonlinear fitting analysis, the sub-dynamic recrystallization models of high-quality GH738 alloy were established. The experimental results show that the decrease of the initial grain size, the increase of the deformation temperature, the extension of the pass interval, and the increase of the strain rate can promote the progress of sub-dynamic recrystallization, and increase the recrystallization volume fraction. Increase the deformation temperature and strain rate can reduce the difference in grain size after sub-dynamic recrystallization, and further improve the uniformity of the microstructure distribution. Based on the experimental results, by using quantitative metallography and nonlinear fitting analysis, sub-dynamic recrystallization models of high-quality GH738 alloy were obtained. The predicted values of the established models were in good agreement with the experimental values, which could meet the actual needs in engineering applications to a great extent.