The invention discloses a novel small assembly detection tool, which comprises a base, and clamping devices and a surface difference detection device arranged on the base, wherein the surface difference detection device comprises a detection block and a first support; one side of the detection block is provided with a reference surface; the bottom part of the detection block is provided with a ridge; a guide groove matched with the ridge is arranged on the first support; the ridge can slide along the guide groove; and the clamping devices are arranged at two ends of the guide groove. Through arranging the detection block capable of sliding in the sliding groove and arranging the clamping devices at two ends of the guide groove, interference of the surface difference detection device and the clamping devices can be effectively avoided, clamping and fixing on the small assembly can be realized, the small assembly can also be detected according to needs, and in comparison with a mode of performing clamping, fixing and detection in the prior art, the working efficiency is higher, the detection intensity is lower, and the making cost is lower.