The utility model discloses a semiconductor laser constant current drive system, including line filter, ACDC and DCDC module, single -chip module, incremental encoder drive module, ADC, DAC module, constant current drive module, liquid crystal display module, information storage module and power detection module. The utility model discloses a synchronous slow starting protection and the short -circuit protection circuit of constant current driver module to and can protect the laser instrument to avoid surge, static, the harm such as overflow based on the limiting current function that single -chip module set up, at utmost extension laser uses.