In continuous variables coherent optical systems,the stability of semiconductor laser directly influences the test results.Injection current and working temperature are the main factors that affect the stability of semiconductor laser.Therefore the laser driver should be highly stable constant current source.Using current feedback control technology,the constant current source has the following advantages:good constant current characteristics,small ripple,strong anti-interference capability,etc.And the temperature control circuit is adopted to control the temperature of the laser,which can ensure the stability of output power.In addition,a series of protection electric circuit is adopted to ensure the reliable operation of the laser.In the system,the monolithic computer is adopted as the main controller.Using digital voltmeter as monitor,the driver has perfect protection function and is easy to use.