This　paper　studies　the　bearing　capacity　of　the　cycloid-pin　gear　drive　mechanism　in　a　rotate　vector　reducer.　First,　the　concept　of　standard　deviation　in　statistics　was　introduced　to　calculate　the　load　distribution　coefficient,　combined　with　the　contact　strength　analysis　theory　and　the　multitooth　contact　load　analysis　theory　of　cycloid-pin　gear　drives,　and　a　calculation　model　of　the　bearing　capacity　of　the　cycloid-pin　gear　drive　mechanism　was　established.　Then,　based　on　the　bearing　capacity　calculation　model,　the　influence　of　the　design　parameters　on　the　bearing　capacity　of　the　cycloid-pin　gear　drive　mechanism　was　systematically　explored.　Finally,　taking　the　bearing　capacity　of　the　cycloid-pin　gear　drive　mechanism　as　the　optimization　objective,　a　multiobjective　genetic　algorithm　was　used　to　optimize　the　design　parameters,　a　more　accurate　optimization　model　of　the　bearing　capacity　of　the　cycloid-pin　gear　drive　mechanism　was　established,　and　the　theoretical　calculation　was　verified　by　finite　element　analysis.　The　results　show　that　the　bearing　capacity　of　the　cycloid-pin　gear　drive　mechanism　is　effectively　improved　after　optimization.