The invention discloses a fixing tool for an engine output chain wheel. The fixing tool comprises a fixing gear ring for fixing the output chain wheel and a supporting block for supporting the fixing gear ring. A connecting portion I used for being connected with the fixing gear ring is arranged on the side, in the transverse direction, of the supporting block, and a connecting portion II used for being hinged to an engine clamping tool is arranged at the other side of the supporting block. The fixing tool is simple in structure, convenient to use and capable of pre-positioning the output chain wheel, assembly and mounting position adjustment are facilitated, the mounting difficulty is lowered, and working efficiency is improved.