A new wavelength beam combining technique for a high-power laser diode bar by using a temperature gradient heat sink has been proposed. The thermal controlling principle of the temperature heat sink has been discussed. It has been proved by experiment that the linear temperature distribution, which generates linear wavelength spread of the output beams from a LD bar, can be obtained by introducing a temperature gradient heat sink and the output beams can be focused into a relative small spot by using the Czerny-Turner beam shaping system.