This　paper　proposes　a　two-dimensional　back-coupled　grating　waveguide　coupler　structure　and　its　parameter　optimization　method.　The　WGC　can　split　a　part　of　the　photons　of　the　incident　beam　uniformly　in　four　directions,　and　make　the　split　photons　back-coupled　to　the　incident　direction.　The　unique　structure　enables　the　WGC　to　be　applied　to　an　array　laser　light　source　that　requires　uniform　back　coupling　of　the　beam　in　four　directions.　In　addition,　through　the　analysis　of　the　parameter　scanning　results　of　the　WGC,　we　found　that　although　the　coupling　efficiency　in　two　directions　of　the　two-dimensional　grating　is　affected　by　the　combined　impact　of　multiple　directional　parameters,　but　some　of　these　effects　are　major　and　some　are　minor.　Using　this　discovery,　we　have　greatly　reduced　the　amount　of　calculation　required　for　parameter　optimization　for　two-dimensional　WGC,　and　provided　a　certain　reference　for　later　researchers.　©　2020　SPIE.