The work aims to propose a solution aiming at the condition of main shaft of cutter roller and bearings of driving parts being easy to wear and break down under high-speed rotation of tobacco cutter, so as to solve the problems such as uneven tobacco thickness, unstable flow rate, cavity, missed tobacco, etc. The vibration signals of normal bearing, bearing with faulted inner ring, bearing with faulted roller and bearing with faulted outer ring were collected respectively through the construction of experimental platform. Based on the calculation of six parameters including RMS, peak value, absolute mean value, pulse index, peak value index and kurtosis index, a new method for calculating the fault degree of the tobacco cutter bearing was proposed. When the speed was 1 772 r/min and 1 797 r/min, the analysis results of time-domain fault degree, frequency-domain fault degree and time-frequency domain fault degree were highly consistent, indicating that the fault degree of inner ring was higher than that of outer ring, and the fault degree of roller was the least. The method shows that the time-frequency characteristic analysis combines the advantages of time-domain characteristic analysis and frequency-domain characteristic analysis, which can effectively improve the efficiency and accuracy of fault diagnosis of tobacco cutter and provide reference value for other rotating mechanical fault diagnosis.