The drive control system of modulated grating Y branch (MG-Y) laser is designedin order to meet the applications and test requirements of MG-Ytunable laser. The computer system was implemented by LabVIEW graphical programming language developed by NI company. The hardware with 64 K high-speed microcontroller as control core, combining with multiple voltage controlled current source module and serial communication module, realize fully programmable and real-time control of the laser drive current. The stability of constant current source part of the designed module is 0.05% in 2 hours at room temperature. For theadjustablecurrent source part, the error range is 3.45 mu A, bandwidth of the input driving signal is 200 Hz, and current tuning rate can reach 3.409 A/s, with maximum signal delay 0.15 ms.