Objective Exploring the contents of chlorogenic acid in Yinchenhao decoction and its regularity of variety decoction time. Methods UPLC method was used. Results The results show that in the range of 0.452～9.040ng，the linear was well between the content of chlorogenic acid and peak area. Conclusion The total concentrations of chlorogenic acid in Yinchenhao decoct medicinal herbs reach maximum at about 25.5 minutes after decocting medicinal herbs starts.