Abstract: Metallurgical flowsheet of tested steel EA1N (/% : 0. 35C, 0. 30Si, 0. 90Mn, 0. 013P, 0. 008S, 0. 15Cr, 0. 10Ni, 0. 10Cu, 0. 04V, 0. 04Al) is 60 t EBT EAF-LF-VD-bottom casting 8.4 t square ingot-hot-rolled to 150 mm x 150 mm billet. The hot compression deformation of steel EA1N with strain rate 0. 01~10s^-1 at 800 ~ 1 300 °C has been tested and studied by using Gleeble-3800 thermal simulation tester to analyze in hot deformation of the steel the relation between flow stress, strain rate and deformation temperature and get the flow tress equation. Results show that in hot compression deformation of steel EA1N with increasing strain rate the flow stress increases and with increasing deforming temperature the flow stress decreases, and as the temperature is more than 1 100 °C and the strain rate is larger than 1s^-1, the feature of dynamic recrystallization occurs obviously on flow stress curves of steel The hot deformation activation energy of steel EA1N is 392.43 KJ/mol.