In order to investigate the performance of the whole laying period of laying hens fed with normal diet added by Daidzein, the following steps are proposed. Firstly data published publicly were extracted. Secondly the 6 prominent indices, laying ratio, weight per egg, feed-egg ratio, 17β-estradiol, T3, and T4, were selected. Thirdly, the increase ratios of those indices were calculated. Fourthly, the increase ratios are integrated according to the age of hens. Fifthly, the data were depicted in the form of pictures and analyzed particularly. Moreover, the data were fitted in the form of polynomial model. Experiments showcase that the performance of laying hens varies with their ages, and the model is capable of fitting data accurately. In the end, the amount of daidzein addition should be selected in terms of the age, and the precise amount can be referred to the graphs in the paper.