The invention provides a single-frequency intracavity frequency doubling laser, comprising a laser crystal (2), a laser resonant cavity consisting of cavity mirrors, a pumping source (1), an intracavity frequency doubling crystal (5), a Faraday rotator (3) and a one-half wave plate (4). The laser crystal (2) is an anisotropic uniaxial crystal, and two light-pass surfaces of the crystal are cut along a certain angle so as to form a non-parallel wedge shape. Because of the birefringence effect of the wedge-shaped laser crystal, the laser stably oscillates and operates with a polarized laser (8), and a polarized laser (9) perpendicular to the polarized laser (8) is inhibited because of geometric optical loss. The laser can also comprise an optical etalon (6) and a Q-switching element (7). The single-frequency intracavity frequency doubling laser designed by the invention has the advantages of the capability of operating stably at single frequency for a long time, high laser polarization degree, high optical-optical conversion efficiency, compact structure, simple regulation, etc., thereby having broad application prospects in the scientific research, national defense construction, bio-medical treatment, information industry and other fields.