OBJECTIVE： To establish a method for simultaneous determination of gallic acid， cinnamic acid and catechin in 3 processed products of Rheum officinale. METHODS： RP-HPLC method was established. The determination was performed on Thermo ScientificTM Hypersil GOLD Dim column with mobile phase consisted of methanol-0.1％ phosphoric acid solution （gradient elution） at the flow rate of 1.0 mL/min. The detection wavelength was set at 278 nm， and the column temperature was 30 ℃. The sample size was 10 μL. RESULTS： The linear range of gallic acid， cinnamic acid and catechin were 0.126 2-1.262 0 μg（r＝0.999 9）， 0.036 2-0.362 0  μg（r＝0.999 9） and 0.177 9-1.779 4 μg（r＝0.999 8）， respectively. Quantitative limits were 25.4， 28.2， 62.5 ng， and detection limits were 6.2， 3.6， 11.8 ng， respectively. RSDs of precision， stability， repeatability and durability tests were all less than 3％. The recoveries ranged from 94.64％-102.71％（RSD＝2.74％， n＝9）， 95.35％-102.49％（RSD＝2.44％， n＝9）， 93.56％-103.66％（RSD＝3.27％， n＝9）. The determination results showed that the contents of gallic acid and cinnamic acid in prepared R. officinale were higher， and the order of both were prepared R. officinale＞steamed R. officinale＞raw R. officinale. The content of catechin in raw R. officinale was higher， and the order of it was raw R. officinale＞ steamed R. officinale＞prepared R. officinale. CONCLUSIONS： The method is sensitive， reliable and reproducible. It can be used to determine the contents of gallic acid， cinnamic acid and catechins in 3 processed products of R. officinale simultaneously.