The present invention discloses a laser power control system includes a laser diode, a monitor photodiode, a bias control circuit, a modulation control circuit, a digital controller, and a laser diode driver. The laser power control system forms an automatic extinction ratio control loop that is configured to control the extinction ratio of the laser diode by comparing a monitor current with a first target current to keep the extinction ratio of the laser diode at the predetermined first target current. The laser power control system forms an automatic power control loop that is configured to control the average power of the laser diode by comparing the monitor current with the second target current to keep the average power of the laser diode at the predetermined second target current.