Objective To probe the similarities and differences in water-soluble organic acids among 5 fruit medicinals with sour taste from rosaceae family [Shanzha (Crataegi Fructus),Mugua (Chaenomelis Fructus),Wumei (Mume Fructus),Jinyingzi (Rosae Laevigatae Fructus) and Fupenzi (Rubi Fructus)]through detecting their pH value and organic acid content.Methods The pH value and content of total titratable organic acids in 5 fruit medicinals were determined by using direct potentiometric method and potentiometric titration.The content of water-soluble organic acids including quinic acid,malic acid,shikimic acid,citric acid,fumaric acid,protocatechuic acid and chlorogenic acid were determined by using high performance liquid chromatography (HPLC) and three-wavelength switching method.Results The pH value of 5 fruit medicinals was in an ascending order as follows:Wumei (2.64) ＜ Shanzha (3.19) ＜ Mugua (3.28) ＜ Fupenzi (4.33) ＜ Jinyingzi (5.06).The content of total titratable organic acids was in a descending order as follows:Wumei (16.2％) ＞ Shanzha (8.39％) ＞ Mugua (7.19％)＞ Jinyingzi (3.97％) ＞ Fupenzi (3.58％).Mugua and Wumei contained nearly all of detected 7 organic acids,and chlorogenic acid was not detected from Jinyingzi and chlorogenic acid and quinic acid were not detected from Fupenzi.The organic acids with higher content in 5 fruit medicinals were,respectively,citric acid (1.09％ in Wumei,0.290％ in Shanzha and 0.272％ in Fupenzi),shikimic acid (0.753％ in Mugua) and quinic acid (0.277％ in Jinyingzi).The results of data analysis indicated that pH value and content of total titratable organic acid showed a good negative correlation (Pearson correlation coefficient was-0.73,P ＜ 0.01).The content changes of total titratable organic acids and citric acid showed nearly equal in 5 fruit medicinal.The comparison in content of each organic acid showed that the changes of spectrums of monomeric organic acid were different among 5 fruit medicinal.Conclusion This experiment conducts a fairly comprehensive analysis on water-soluble organic acids in 5 fruit medicinal,provides thinking and accumulates experimental data for the systematical characterization and quantification of important content in Chinese medicinal with sour taste.Meanwhile the experiment provides the evidence for Pharmacopoeia of People's Republic of China that citric acid can be taken as the quality marker for Wumei and Shanzha.