Abstract: The thermal simulation experiment of the influence of the cooling rate and the final cooling temperature after the large deformation on the microstructure of EH47 steel plate was carried out on a laboratory thermal simulator. The microstructure of the test steel was observed by OM and TEM. The results show that the steel plate microstructure is mainly composed of acicular ferrite,bainite and a small amount of granular ferrite. With the increase of cooling rate and final cooling temperature, the bainite increases. When the final cooling temperature is 650℃, there is more bainite, less acicular ferrite and finer and denser strip bundles in the experimental steel. The larger the cooling rate is, the more uniform the mixed microstructure of acicular ferrite and bainite is, and the smaller the grain size after deformation. There are a small amount of precipitates between grain boundaries. When the cooling rate is 10℃/s, the obvious M/A islands and twin microstructures in the steel plate can be observed by TEM.