Abstract: In order to find a new method of rapid determination on coal hardiness coefficient (referred to "f value"), for achieving in-situ determination of coal f value in the underground working face, carried out f value rapid determination method (areferred to "crushing method") laboratory research by high-speed rotating and mechanical crushing of coal sample broken way.According to the actual situation on site and the coal sample crush orthogonal experiment results, the optimal combination of grinding parameters on coal sample crushing time, coal sample quality and grinding speed was established.Based on this, crushing experiments was carried out in coal samples collected from different coal seams in different mines.Correlation between coal f value and coal quality accounted for the proportion with different size fractions after coal sample crushing was studied.The results show that the exponentiation fitting relation of coal cinder quality accounting less than 0.5 mm after the coal sample crushed and coal f value is optimal, and the fitting degree reaches 0.931 1; at the same time, the current measurement standard "drop hammer method" is used to verify the measurement results of crushing method.f value, the measurement error is not more than 8%, it is verified that the established "crushing method" for rapid determination of f value is reasonable and feasible.