The three-rings and Medium-speed micro powder grinder is using the latest technological advances in grinding equipment, the three-rings and medium-speed micro powder grinder is widely used in grinding barite, limestone, kaolin, ceram, and slag, etc. Three-rings and medium-speed micro powder grinder is not different from other micro powder grinder. The three-rings and the rolling pressure ration of Medium-speed micro powder grinder is 1.2 times higher than that of the raymond grinder under the same power condition and the production output is raised to substantial degree. When a certain degree of wear of roller and ring of the Three-rings and Medium-speed micro powder is effected, The three-rings and Medium-speed micro powder is recommended to adjust the length of the spring to maintain the constant pressure between the roller and the ring. As a result, The stable output and fineness of the three-rings and Medium-speed micro powder are ensured.