The dynamic recrystallization(DRX) and the equations of flow stress are developed by hot torsion. The quantitative relationships between the flow stress and processing variables are estimated. As processing variables, we focused on the strain rate (c), temperature (T), and strain (c) of type 304 and 316 austenitic stainless steels. The torsion tests were performed to study the high temperature dynamic softening behavior in the temperature ranges of 900 - 1200 degreesC and the strain rate of 5.0 x 10(-2) - 5.0 x 10 /sec. The dynamic recrystallization is dominant in the steady state region of flow stress curve and it plays a major role in the progress of flow stress. We developed some equations to predict the dynamic recrystallization and flow stress based on the modified Kohnogorov-Johnson-Mehl-Avrami's (KJMA) one. The calculated curves have a good agreement with observation.