The invention discloses a DFB laser based on surface gating. The laser is of a ridge waveguide structure, and comprises a substrate, a lower waveguide cover layer, an active layer and an upper waveguide cover layer from the bottom up, wherein Bragg grating is etched in the surface of the ridge waveguide; the ridge area adopts high refractive material, so that the gating has a large coupling coefficient; no electrode is formed on the ridge waveguide, and the electrodes are positioned on two sides of the ridge waveguide; a groove is etched between the ridge waveguide and each of the electrodes on two sides; in the laser, the lower waveguide cover layer comprises one or more current limitation areas, or a buried tunnel junction is manufactured in the upper waveguide cover layer to limit current. According to the laser provided by the invention, secondary epitaxial growth of the material is not needed, the manufacturing technology is simple and convenient, and thus the manufacturing cost of the device is reduced, and the reliability of the device is improved. In addition, the laser provided by the invention can acquire the maximum coupling coefficient, so that the laser performance of low threshold and high-speed direct adjustment can be acquired in the case that the cavity length of the laser is extremely short.