Abstract: According to the available character identification method of the coal and rock hardness could not meet the requirements of the automatic height- adjust ment technology realized by the cutting drum of the coal shearer, an identification method of the coal and rock hardness was provided with the energy features of the vi bration signal time- frequency domain in the ranging boom. A self developed mine vibration accelerometer with a MA certificate was applied to the tests in the undergro und mine. With the vibration acceleration signal measured at the ranging boom of the coal shearer in the fully mechanized coal mining face as the study object, the wav elet packet signal analysis method was applied to have the solution signal of the time- frequency domain with four frequency contents from No.3 strata. According to th e function expression after the coefficient restructured, the signal energy at each frequency section was calculated as the eigenvector and was applied to determine the vibration features of the ranging boom during the coal and rock cutting period of the coal shearer. Based on the measured data of MG180 1420- BWD thin seam shearer operated in Nantun Mine of Yanzhou Coal Mining Group, The results showed that the energy feature vector of the wavelet packet time- frequency domain would be sens itive to the hard.