The utility model relates to a detection tool, in particular to a detection tool for detecting the precision of a differential assembly and the bounce of a gear ring. The detection tool comprises a bottom plate, a positioning body, a bottom column, a stand column, a cross beam, a torsion spring, a first gauge stand used for installing a dial gauge, a spherical measuring head, a top column, a guiderod, a lifting platform, a second gauge stand used for installing the dial gauge and a positioning seat. The detection items are many, the precision after the left shell and the right shell are assembled can be detected, the tooth profile radial run-out after the gear ring is assembled can also be detected, the universality is good, measurement of various products can be achieved by replacing thepositioning body and the positioning base, operation is convenient, positioning of the differential mechanism assembly depends on gravity attachment, positioning errors are eliminated, and the measurement precision is improved.