The invention relates to a method for evaluating quality of FRUCTUSSCHISANDRAE SPHENANTHERAE in commercially available Chinese patent medicines by using a flash-gas chromatography. The method comprises the steps of putting a powdered or liquid Chinese patent medicine sample, which contains the FRUCTUSSCHISANDRAE SPHENANTHERAE, into a pyrolyzer, and placing the pyrolyzer at a sample inlet of a gas chromatograph; when the temperature of the pyrolyzer reaches a certain value, carrying out sample introduction; detecting the sample by using the gas chromatograph to obtain a gas chromatogram; carrying out qualitative analysis on a lignan component in the Chinese patent medicine sample by using standard material retention time, and determining the corresponding peak positions of anwuligan, deoxyschizandrin and schisantherin in the gas chromatogram; (2) then, using the flash-gas chromatography to carry out quantitative analysis on the deoxyschizandrin and the schisantherin in the Chinese patent medicine sample by means of an external standard method; if the quantitative result shows that the relative contents of the deoxyschizandrin and the schisantherin in the Chinese patent medicine sample are within a range of 1.50-2.0, proving that the quality of the FRUCTUSSCHISANDRAE SPHENANTHERAE in the Chinese patent medicine sample is better, and otherwise, proving that the quality of the fructus schisandrae in the Chinese patent medicine sample is poorer. The method has the characteristics of being simple, environmentally friendly and efficient.