A rapid and convenient method to separate and quantify ursolic acid (UA) and oleanolic acid (OA) of cornus (Macrocarpium officinale (Sieb. et Zucc.) Nakai), a traditional Chinese medicine and food materials, was established by reversed-phase high performance liquid chromatographic (RP-HPLC). The Linear ranges were 1.01–6.06μg/μl for UA and 0.51–2.55μg/μl for OA with good correlation. The average recovery rates were 103.0% of UA and 97.9% of OA, respectively. The precision and the repeatability of the analytical method were satisfied. Samples of cornus at different developmental stages were detected, and the UA contents varied from a high of over 0.520% to less than 0.107%, while OA contents varied from 0.221% to 0.050% during the fruit growth. This study showed that the contents of UA and OA varied considerably with fruit development, especially with the development of exocarp, and the results indicated that the appropriate picking time was in later September. The distinct contents of UA and OA in different parts of cornus (exocarp, sarcocarp, and core) suggested the two compounds mainly located in exocarp of the fruit.