A new nickel base superalloy was prepared by spray forming process, which was then treated by hot-isostatic pressing. The hot compression tests were conducted under various testing conditions by a Gleeble-3500 thermal simulation instrument. The deformation mechanisms were studied by optical microscope, scanning electron microscope (SEM), and transmission electron microscope (TEM). The results show that the actual deformation temperature is higher than the nominal deformation temperature at the high strain rate of 10 s-1 due to the friction heating and thus the dynamic recrystallization (DRX) is promoted. The twin grain formed at the high strain rate can further excite sliding deformation, while lots of dislocation formed in subgrains can coordinate the deformation to ensure its proceeding. The model of the DRX grain size is established as lnd=8.26–0.058lnZ. It shows that at the fixed testing temperature, with the increase of Z parameter, viz. the increase of strain rate, the DRX grain is refined and the deformability is enhanced, which is consistent with the testing results.