The application discloses a narrow linewidth semiconductor laser that solves the problem in the prior art that using a long long-cavity structure to achieve a narrow linewidth in a waveguide results in increased propagation loss of light in the waveguide. The narrow linewidth semiconductor laser comprises a semiconductor light source and a passive filter. The passive filter comprises a waveguide grating coupler and a Bragg grating reflector. The semiconductor light source is configured to be connected to the passive filter. The waveguide grating coupler is configured to radiate the received light emitted by the semiconductor light source to the Bragg grating reflector and return the reflected light of the Bragg grating reflector back to the semiconductor light source. The narrow linewidthsemiconductor laser, by means of filter feedback and the three-dimensional space structural design, can not only avoid the long-cavity design to achieve low loss, but also is easy to integrate by means of the silicon-based and excellent spatial structure, thereby enabling large-scale photon integration.