The invention provides a switch cabinet state monitoring and diagnosing method and system. The switch cabinet state monitoring and diagnosing method comprises the following steps that a reference sequence x<0>=[x<1> x<2 > x<3>... x] is determined; data of each monitoring unit collected by a sensor module are obtained; a comparison sequence x=[x x x... x] is determined; the difference delta o(tn) of the reference sequence and the comparison sequence is calculated; the correlation coefficient epsilon o(tn) is calculated; the relevancy gamma i is calculated; the sequence of defect causes of a switch cabinet is ranked; the defect cause ranking first is taken as diagnosis data; and the diagnosis data are displayed. The switch cabinet state monitoring and diagnosing method and system have the beneficial effects that a plurality of monitoring units are arranged on the switch cabinet, a plurality of signals of the switch cabinet can be simultaneously detected, and multidimensional data formed by the signals are comprehensively processed and analyzed to monitor the operation state of the switch cabinet and diagnose the fault defects of the switch cabinet.