The invention discloses a method for studying the compatibility relationship of compound Chinese medicine formulae such as Kouyanqing preparations and screening an optimal formula. The method comprises the following steps that firstly, differential samples with the ingredients in different ingredient proportions are built according to the compound Chinese medicine formulae such as the Kouyanqing preparations by taking the mass percentage content of all the ingredients as variable factors and adopting a uniform design method; secondly, medicine efficacy data of all the differential samples are obtained through pharmacodynamics study; thirdly, the relevance between the content of all the ingredients of the differential samples and the medicine efficacy is analyzed through a mathematical statistic method, contribution of all the ingredients to the medicine efficacy and the primary and secondary relationship of the ingredients are determined, then the compatibility regularity of the formulae is determined, and the optimal compatibility relationship is screened to obtain the optimal formula. The method is based on the fact that the raw medicine materials of Kouyanqing grains are relevant to the anti-inflammation medicine efficacy, the functions and positions of all the medicine materials in the formula are scientifically analyzed, the compatibility relationship of the formula is illustrated, it is confirmed that the proportion of the original formula is optimal, and a basis is supplied to screening of the optimal formula.