The invention relates to an ultrahigh frequency partial discharge detection equipment mode identification function test system and test method based on an avalanche triode. The test system is composed of a trigger circuit, a negative pulse circuit, a positive pulse circuit and an ultrahigh frequency emission antenna. The test method realizes the purpose of testing the mode identification function of detected ultrahigh frequency partial discharge detection equipment by generating and emitting ultrahigh frequency signals with metal tips or a suspension potential body partial discharge mode by use of the test system, and comparing whether the ultrahigh frequency signal partial discharge mode actually generated and emitted by the test system is consistent with an ultrahigh frequency signal partial discharge mode detected and determined by the detected ultrahigh frequency partial discharge detection equipment. The test system and method provided by the invention have the advantages of safe test process, scientific test items, fast test speed, low test system price and the like.