An optical network-on-chip, an optical router, and a signal transmission method. The optical network-on-chip includes: N2 intellectual property IP cores, N2/2 gateways, and N2 optical routers. The N2 optical routers form two subnets, and every N2/2 optical routers form one subnet. Each gateway in the N2/2 gateways is connected to every two IP cores in the N2 IP cores, where IP cores connected to different gateways are different, and the two IP cores connected to each gateway are in one-to-one correspondences with the two subnets. The N2/2 gateways are in one-to-one correspondences with the N2/2 optical routers in each subnet in the two subnets, where each gateway is connected to an optical router that is in each subnet and that is corresponding to each gateway.