The invention relates to a test tool for an upper crossbeam connecting plate at back of an automotive floor. The test tool comprises an iron stand and a pin tool, wherein wheels are arranged at the lower part of the iron stand, and a test tool body, clamping jaw bodies and a limiting seat are arranged at the upper part of the iron stand; the test tool body is arranged at the center of the iron stand, and the clamping jaw bodies are distributed around the test tool body; each clamping jaw body comprises a clamp seat, and the upper part of the clamp seat is connected with a clamp head; a clamp is arranged on the clamp head, and the clamping jaw bodies include two fourth clamping jaw bodies and two second clamping jaw bodies; the two fourth clamping jaw bodies are arranged at the front part of the upper end surface of the iron stand, and the two second clamping jaw bodies are arranged at the back of the upper end surface of the iron stand; a tapered pressure head is arranged on a clamp of a second clamping jaw, and a pressure head is arranged on a clamp of a fourth clamping jaw; a main positioning hole, a test hole and an auxiliary positioning hole are sequentially formed in the center of the upper surface of the test tool body from the front to the back. The test tool provided by the invention has the advantages of high positioning precision, good clamping effect and the like, the test efficiency of the upper crossbeam connecting plate at back of the automotive floor can be enhanced, the manipulation is convenient, the clamping and positioning are reliable, and the smooth test is ensured.