Irradiating the mixture of methane and bromine with 9.6m 5(22) line of TEA C02 laser, we excite CH2D3 selectively and increase the rate of the bromination reaction of CH3D2 so that deuterium is enriched. The reaction mixture consists of 30 Torr CH4, 30 Torr CH2D3 and 10 Torr Br3. The enrichment factor is 1.48.