Abstract: In ore washing & coal preparation sector, the Hancock formula is exclusively used for evaluation of flotation efficiency.However, the formula is incomplete in representation because the “misplacement” phenomenon in coal separation process is not taken into account.In order to explore the improved flotation efficiency evaluation method, test is made on floatability of flotation feed, concentrate and tailings.Based on the ash composition of each of the three materials obtained through the test, a total flotation efficiency method based on the product of correctly placed efficiency of concentrate and that of tailings is proposed.The completeness and effectiveness of the proposed method have been verified by both theoretical analysis and test result.