The content of polyphenolic compounds including chlorogenic acid,vitexin-4″-O-glucoside,vitexin rhamnoside, rutin, vitexin, hyperoside in leaf of Crataegus pinnatifida Bunge var.major N.E.Br.at different times was determined by HPLC. The results show that the content of polyphenolic compounds in different times is various. In April, the total content of polyphenolic compounds and the contents of chlorogenic acid,vitexin-4″-O-glucoside,vitexin rhamnoside, rutin reach the peak.And the content of every compound and the total content of these compounds decrease gradually with the plant growing, and reach the lowest point in July to August. Therefore, in order to extract polyphenolic compounds, the optimal harvest time for C. pinnatifida var.major leaf is April.