Abstract: High temperature deformation behavior and dynamic recrystalization behavior of an E40 steel plate used for offshore platform were studied by single-pass compressive testing on MMS-200 hot simulation tester. A perfect austenization temperature for the tested steel was determined. The results show that critical shear stree for dynamic recrystalization decreased with the increase of deformation temperature. The start temperature for dynamic recrystalization varied in the range of 900-950 ℃. The true stress-true strain curve declined at 850 ℃, which could be explained by strain-induced ferrite transformation, and when deformation temperature was above 900 ℃, dynamic recrystalization led to true stress-true strain curve declining. Ideal deformation temperature of the steel was 1 200 ℃.