OBJECTIVE： To preliminarily study the stability of 3 pieces of Chinese medicinal formula （CMF） after decoction， and provide reference for guaranteeing storage quality of decocted liquid and improving safety of drug use. METHODS： 3 representative formulas of Gegen Huangqin Huanglian decoction （A formula）， Wuling powder （B formula） and Didang decoction （C formula） from Shanghan Zabing Lun were selected， the decocted liquid were stored under ambient temperature （25 ℃） and refrigerated temperature （4 ℃） after decocting by automatic boiling-machine and packing. The microorganism， precipitation， pH and contents of total flavonoids， alkaloid， polysaccharide， total protein after 1， 7， 14， 21， 28 d were detected. RESULTS： Compared with the first day， contents of total flavonoids， polysaccharide in formula A at ambient temperature group were significantly increased on the 28th （P＜0.05）， content of polysaccharide in refrigerated temperature group was significantly increased （P＜0.05）. Content of polysaccharide in formula B at ambient temperature group was significantly decreased （P＜0.05）. The pH and content of total flavonoids in formula C at ambient temperature group and refrigerated temperature group were significantly increased （P＜0.05 or P＜0.01）. Other indexes showed no obvious changes during the trial period. CONCLUSIONS： Under ambient temperature and refrigerated temperature， liquid ingredients of above decocted CMF will change when storing for 4 weeks. It indicates that the storage time of decocted CMF should not be more than 3 weeks.