The invention discloses a semiconductor rectifier. The semiconductor rectifier comprises a first conductive type of light-doped epitaxial layer, wherein a plurality of grooves are transversely formed in the upper part of the epitaxial layer at intervals, the first grooves are filled with conductive poly-silicon, isolation layers are arranged between the conductive poly-silicon and the first grooves and upwards protrude to form dielectric walls, conductive poly-silicon side walls are arranged on the two sides of the dielectric walls, a second groove is formed in a region between the upper part of the epitaxial layer and the conductive poly-silicon side walls, a transverse uniform doping region and a gradient doping region are arranged at the upper part of the epitaxial layer, channels are formed between the gradient doping region and the isolation layers, and isolation regions are arranged among the lower part of the epitaxial layer, the transverse uniform doping regions, the gradient doping regions and the isolation layers. With the adoption of a groove grid structure, the semiconductor rectifier has the characteristics of short channel and channel doping gradient distribution and excellent positive conduction. The invention also discloses a fabrication method of the semiconductor rectifier, and the process is simple in step, large in process window, few in photoetching frequency and low in fabrication cost, and is easy to control.