The Semiconductor laser frequency stabilization is the important study topic because of its increasing popular. We introduce a simply experimental setup method of the frequency stabilization of a 780 nm diode laser by only a tiny current in the laser audio modulation, photodiode receiver, and locking the transmission peaks. Use this method, the laser can be locked to the resonance peak of the Fabry-Perot cavity. The linewidth of laser is below 400 kHz, and it runs continually above 3 hours.