A digital control current supply is designed for driving semiconductor lasers by taking the TMS320F28335 as a control center,which consists of a guiding light module,a phonetic module,a liquid-crystal display(LCD) module and a keyboard module. The phonetic module and light module are responsible for prompting the working condition of the system,the LCD is used to show the actual current and setting current,and the keyboard module is taken to control the start-up, turn-off, current setting and current adjustment. In circuit design，the deep feedback theory is researched to greatly enhance the stability and two MOSFET are designed to neutralize their own leakage current, decrease the current deviation(less than 0.5%) and optimize the linear dependence between voltage and current. In software design, the PID algorithm is employed to shorten the time to establish dynamic equilibrium for the system. The system can provide complete protective measures, such as surge-prevent, power on/off-prevent, time delay soft start, over current protection for ensuring the LD to work stably and reliably. During the driving test, the LD can work in a steady state without center wavelength drifting and driving current fluctuation.