The hot compression deformation of U720Li superalloy was investigated systematically. Through by the analysis and the calculation of the mechanical behavior and the microstructure evolution during hot compression deformation, the variation of strain rate sensitivity exponent m, activation energy Q and grain size exponent P values at different strain rates and different temperatures were obtained. The hot processing map based on dynamic materials modeling was drawn while high-temperature deformation mechanism maps incorporating dislocations inside grains were obtained. The processing map was used to analyze the hot deformation behavior and to determine processing instability regime and appropriate processing regimes. Within appropriate processing regime, based on the elevated temperature deformation mechanism maps, the Burgers vector compensated grain size, the modulus compensated stress and the dislocation quantities of U720Li superalloy at different temperatures, the hot deformation mechanisms were elucidated.