Hot workability of powder metallurgy molybdenum in the temperature range of 900-1450 oC and strain rate range of 0.01-10 s-1 was investigated by hot compression tests on a Gleeble-1500 thermal mechanical simulator. According to experimental results, the dynamic recrystallization (DRX) behavior of powder metallurgy molybdenum was studied and its θ-σ and ?θ/?σ-σ curves were established. Based on working hardening rate-stress (θ-σ) and working hardening rate-strain (θ-ε) curves, the critical strain εc of DRX was determined. The average grain size (D) and Zener-Hollmon parameter (Z) during DRX process obey the following equation: lnD=3.65597–0.05409lnZ; these researches provide fundamental data for cogging and hot working technology of powder metallurgy molybdenum.