Abstract: The thermal simulation compression test of cast-GH4720Li superalloy was executed by Gleeble 3800 thermal simulator to obtain the stress-strain data at the hot deformation temperature of 1080-1180 ℃ and strain rate of 0.01-10 s^-1.The flow behavior of the alloy was analyzed and DRX volume fraction prediction model during the dynamic recrystallization was established. The results show that the flow stress of cast-GH4720Li alloy increases firstly and then reduces with strain rising at different temperatures and strain rates, displaying evident softening features of DRV and DRX. The critical strain for DRX exhibits a linear relationship with the peak strain of the compression. Based on the principles of work hardening and softening of DRV and DRX, the percentage of DRX during the hot deformation is calculated, and the modified Avrami model of DRX is established by the calculated data, which provides a better quantitative prediction for the hot deformation of the alloy. The predicting values of DRX model are in constant with the results of microstructural experiments, and the established model can be used to guide the billet forging process of the alloy.