Ni base superalloy is one of the most important key materials for hot section parts in various applications. As for cast and wrought material, it is well known that grain size distribution and recrystallization ratio as well as precipitation condition have considerable effect on mechanical properties. The deformation and dynamic recrystallization behavior of representative Ni base superalloy, Waspaloy were revealed through various kinds of hot compression tests and quantitative relationship available for numerical calculation technology was derived. Dynamically recrystallized grain diameter depended on temperature, strain rate and was independent of the initial grain diameter and strain. The grain diameter could be expressed as a function of the temperature compensated strain rate, i.e., Zener–Hollomon parameter quantitatively. Avrami-type equation was available for comprehensive and quantitative expression of dynamic recrystallization transition. The approximation was a function of the given strain and strain for the 50% recrystallization which depends on the initial grain diameter and Zener–Hollomon parameter.