Abstract: Objective:To establish a method for evaluating the productivity ratio of plate count agar(PCA)based on reference materials. Methods:The reference material of Escherichia coli(E. coli)was tested using PCA,and then the productivity ratio of E. coli on the evaluated PCA was calculated according to the formula. The repeatability and reproducibility of the established method were verified in the study. In addition,the productivity ratio of 9 brands PCA was evaluated by the established method. Results:The RSD of repeatability of the established method was 9.09%,and the RSD of reproducibility was 14.42%. The productivity ratios of 9 brands PCA could face with the requirements of 0.83≤P_R≤1.17,although there were differences between them. Conclusion:A method for quality control of the culture medium based on the reference material was successfully established,which showed a good repeatability and reproducibility,and could effectively evaluate the productivity ratio of PCA rapidly and efficiently.