Abstract: Aiming at problem of excessive vibration during operation of Linhai 4LZ-7A crawler rice combine harvester, vibration signals from harvester's cab were first collected and analyzed through vibration signal acquisition software to obtain characteristic frequencies．This also determined main excitation sources such as engine, header, vibrating screen, threshing drum and other key components．ANSYS Workbench modal analysis was conducted on these key components to obtain main modal frequencies, which were compared with characteristic frequencies from cab vibration signals．Results revealed that the first-order frequency of 40.75 Hz, second-order frequency of 84.95 Hz and fifth-order frequency of 122.56 Hz of threshing drum may resonate with external excitation frequency of 40.96 Hz from engine．Vibration screen's first-order frequency of 13.90 Hz was close to drum's external excitation frequency, while its sixth-order modal frequency of 38.02 Hz was close to engine's fundamental frequency．These similar modal frequencies could all cause resonance, thereby increasing vibration in combine harvester's cab．The fifth-order modal frequency of cutting table was 12.13 Hz, which was close to the first-order modal frequency of vibrating screen of 13.90 Hz．The sixth-order modal frequency of cutting table was 16.03 Hz, which was close to the second-order modal frequency of vibrating screen of 18.44 Hz．Similar modal frequencies between cutting table and vibrating screen could cause resonance．Research conclusion provided a basis for key components design and working parameters optimization of combine harvester．