Abstract: A method has been described for accurate determination of Deuterium abundance in the Lithium Hydrogenate Deuterate by mass spectrum analyzing technology.The expression of Deuterium abundance has been presented by MAT-250 gas mass spectrometry of low resolution.The results indicate:relative standard deviations are better than 0.2% for gas samples of different deuterium abundance.Measure value is believable in the error range of 0.2%.