The invention discloses a tunable DFB laser driving device with high power and low power consumption. A current sampling circuit is used for feeding back and obtaining the injection current signal of a laser to be compared with a setting signal passing through a D/A converter circuit so as to obtain a deviation value; a current regulating circuit is used for carrying out constant-current control on the current according to the deviation value and sending the signal to an MCU control circuit; the MCU control circuit is used for changing the MAX5142 output setting voltage of the D/A converter circuit so as to regulate the injection current of the laser; a feedback sensor is used for feeding back a laser tube real-time temperature signal to an MCU controller; the MCU controller is used for contrasting a setting temperature with a feedback actual temperature so as to obtain a temperature deviation value and carrying out temperature control on a laser tube through a temperature controller and an actuating mechanism according to the temperature deviation value. The device solves the problem that a light source is complicated in a plurality of needed wavelength laser devices, meanwhile a turn-off protection circuit is introduced to be started, the laser and other components are protected, and the system characteristics are improved.