Abstract: In order to develop a narrow range of parameters of controlled rolling and controlled cooling process in laboratory, the influences start rolling temperature, finish rolling temperature, coiling temperature, cooling rate from finish pass to coiling and cooling rate after coiling on microstructure and hardness of 65Mn steel were studied by thermal simulation tester. The results show that the most influential parameters for hardness of 65Mn steel was cooling rate after coiling. The higher start rolling temperature, finish rolling temperature and coiling temperature were beneficial for the growth of original austenite grain and recrystallization grain, and then the grains size after rolling was bigger, this lead to the decrease of hardness and strength. Under the same rolling parameters, with the decrease of cooling rate after coiling, the average grain size increased obviously and the content of proeutectoid ferrite increased in some degree. The best controlled rolling and controlled cooling parameters were start rolling temperature of 1 170 ℃, fininsh temperature of 890 ℃, coiling temperature of 680 ℃, cooling rate from finish rolling to coiling of 10 ℃·s-1, cooling rate after coiling of 0.05 ℃·s-1; under the parameters, the hardness of the tested steel was 19.9 HRC.