Semiconductor lasers have been widely used in quantum information, precision measurement, optical sensing and other fields due to the advantages of large wavelength coverage, easy tuning, small size, light weight, simple structure, low power consumption and long working lifetime. Since the output frequency of free-running semiconductor laser fluctuates widely, it is necessary to stabilize its frequency by feedback control. However, the traditional feedback control system has some disadvantages, such as complex structure, large size and poor stability, so we construct a stabilization system of external cavity diode laser based on a Field Programmable Gate Array (FPGA) module. In this paper we use PyRPL, an open-source software package, to provide an arbitrary signal generator, a lock-in amplifier, a Proportional-Integral-Differential (PID) controller and an oscilloscope based on STEM125-14. And the saturated absorption spectrum of cesium atoms is used as the reference frequency for the stabilization system to lock a semiconductor laser. The arbitrary signal generator is used to generate sawtooth signal to scan the external cavity length of the semiconductor laser, thus realizing the tuning of the laser frequency. The lock-in amplifier module is used to generate sinusoidal signal to modulate laser current and to demodulate the modulated signal of the saturated absorption spectrum, and then error signal through filtering is generated. The PID module is used to employ the feedback signal to control the laser current, which makes the laser frequency be stabilized to the atomic transition lines. Using the FPGA module as a core circuit device, the frequency of laser is stabilized to the frequency of crossover line of |62S1/2,F=4>→|62P3/2,F=4,5> and the transition line of |62S1/2,F=4>→|62P3/2,F=5>. The frequency fluctuation of the locking laser within 80 s is 3.0(0.3) MHz. The Allan deviation and frequency spectra of the error signal when the laser is locked and unlocked are compared and the results show that frequency fluctuation can be suppressed effectively when the feedback is applied. The system with advantages of high integration, compact and easy to use, can be used in a variety of locking systems.