The invention discloses a discharge capacity monitoring and collecting method for ultrahigh frequency local discharge, In the method, the pulse number exceeding the comparative level in each phase interval of an industrial frequency period is obtained through level comparison by analyzing the characteristic of an ultrahigh frequency local discharge signal and scanning a comparative level and the local discharge signal; the pulse number of different comparative levels is obtained through gradually increasing the comparative level, if no comparative pulse is output, the local discharge amplitude is smaller than the set comparative level, thus, a three-dimensional spectrogram of the ultrahigh frequency local discharge signal can be obtained through the pulse numerical values under different comparative levels; and conventional high-speed large-capacity data acquisition is changed into high-frequency pulse comparison counting, thereby simplifying an ultrahigh frequency local discharge monitoring circuit. A device provided by the invention has wide use range, higher accuracy, simple structure, smaller size, low cost, simple operation and convenient carry.