The invention discloses a suspension positioning mechanism, which comprises a motion assembly and a fixed assembly, and is characterized in that the motion assembly comprises a body, at least two contact blocks arranged at one side of the body, a groove, a hook with one end being accommodated in the groove, and a plurality of height adjustable sliding wheel assemblies arranged at the bottom of the body; one side of the fixed assembly comprises supporting assemblies, a lifting assembly, a hook positioning assembly, a hook shifting lever assembly, an X-direction positioning member and a Y-direction positioning member, wherein the supporting assemblies and the lifting assembly are matched with the contact blocks, the hook positioning assembly and the hook shifting lever assembly are matched with the hook, and the X-direction positioning member and the Y-direction positioning member are used for positioning the motion assembly. According to the invention, the positioning stability and the reliability of the motion assembly can be effectively improved through setting the contact blocks and the supporting assemblies with a balancing function, and the lifting assembly is set at the same time so as to improve the repeat positioning, assembling and disassembling speed of an optical system; and the plurality of height adjustable sliding wheel assemblies are adopted, so that the overall position of the motion assembly is effectively adjusted, the motion assembly is prevented from colliding with a part above the fixed assembly in the positioning process, the operation is simple and convenient, and the effect is stable and reliable.