Narrow linewidth semiconductor lasers are widely used in the field of radar and sensor. So the research of narrow linewidth laser is necessary. Using electric feedback structure, and with a frequency discriminators, the center wavelength is stablized. The laser from frequency discriminators is converted to current by photoelectric detector. Different signals of inherent detector and the current are injected into laser to reduce the frequency noise. So the laser line width of 0.5 nm reduces to 0.08 nm.