Abstract: The new technique for analysing light hydrocarbons introduced in the paper is of characteristic, which differs from techniques currently used home and abroad. It is based on the principles of energy conversion in thermodynamics. Firstly an original rock sample is directly put into a tube of degasification device, and the deabsorption of light hydrocarbons under low vaccum negative pressure is accomplished by use of a high speed rotation agitator. Then certain volume of deabsorbed gas is injected into a capillary column of high resolution and chromatography and determination and data process are performed under optimum conditions.