The invention relates to a light-cured composite resin for an oral cavity by using single crystal diamond as a filler, which belongs to the field of a medical oral cavity material. The resin comprisesThe invention relates to a light-cured composite resin for an oral cavity by using single crystal diamond as a filler, which belongs to the field of a medical oral cavity material. The resin comprisesonal medical standard that flexural strength value of the composite resin should be equal to or greater than 50 MPa, even can satisfy the requirement for the strength (greater than 80 MPa) of occlustional medical standard that flexural strength value of the composite resin should be equal to or greater than 50 MPa, even can satisfy the requirement for the strength (greater than 80 MPa) of occlusal restoring materials.al restoring materials.a resin matrix and the filler, wherein the filler comprises coupling barium glass powder and coupling diamond. The composite resin is characterized in that the coupling diamond comprises coupling sin a resin matrix and the filler, wherein the filler comprises coupling barium glass powder and coupling diamond. The composite resin is characterized in that the coupling diamond comprises coupling single crystal diamond which accounts for 15-25 percent of the total weight of the composite resin, coupling glomerocryst diamond which accounts for 0-1 percent of the total weight of the composite resingle crystal diamond which accounts for 15-25 percent of the total weight of the composite resin, coupling glomerocryst diamond which accounts for 0-1 percent of the total weight of the composite resinand coupling nanometer diamond which accounts for 0-1 percent of the total weigh of the composite resin. The single crystal diamond is added as the functional filler, so that the flexural strength an and coupling nanometer diamond which accounts for 0-1 percent of the total weigh of the composite resin. The single crystal diamond is added as the functional filler, so that the flexural strength and the micro hardness of the prepared composite resin are observably increased, the maximum flexural strength value of the composite resin, which can reach 112.5MPa, can satisfy the requirement in a nad the micro hardness of the prepared composite resin are observably increased, the maximum flexural strength value of the composite resin, which can reach 112.5MPa, can satisfy the requirement in a nati