The utility model relates to a semiconductor power device and especially relates to a fast recovery diode. The fast recovery diode comprises a substrate and a P area. The P area forms on the substrate. The substrate is a non-uniform doped N-type silicon substrate. The N-type silicon substrate comprises a substrate N- layer and a substrate N+ layer which are successively distributed from bottom to top. The P area comprises a corroded P+ area and a P- area which are successively arranged from top to bottom. The P+ area and the substrate N- layer form a P+N- junction. Under the condition that two side concentration of the P+N- junction is guaranteed, through carrying out corrosion on silicon of the P+ area, an amount of impurities of the P+ area is reduced so that a cavity number which is injected into a N- area from the P+ area is decreased. Through less recombination centers, an enough reverse direction recovery speed is reached. Simultaneously, decrease of the conductivity modulation cavity number is participated in so that a temperature coefficient of a pressure drop approaches zero and parallel connection is easy to achieve.