To establish a method for simultaneous determination of dehydrotumulosic acid, polyporenic acid C, 3-epi-dehydrotumulosic acid, dehydropachymic acid and pachymic acid in Poria, a RP-HPLC method detected by UV wavelengths switch had been developed, including 210 nm (48-55 min) for pachymic acid and 241 nm (0-48 min) for dehydrotumulosic acid, polyporenic acid C, 3-epi-dehydrotumulosic acid, dehydropachymic acid, separately. The system consisting of a Kromasil C18 column (250 mm x 4.6 mm, 5 microm) and a mixture of acetonitrile and 0.05% phosphate acid as the mobile phase was adopted; The flow rate was 1.0 mL x min(-1). The linear response range was 30.5-610.0 microg x mL(-1) (r = 0.999 6) for dehydrotumulosic acid, 12.66-253.2 microg x mL(-1) (r = 0.999 5) for polyporenic acid C, 2.99-59.7 microg x mL(-1) (r = 0.999 7) for 3-epi-dehydrotumulosic acid, 6.13-122.5 microg x mL(-1) (r = 0.999 5) for dehydropachymic acid and 11.3-226.0 microg x mL(-1) (r = 0.9995) for pachymic acid. The average recoveries of these compounds were 98.5% (RSD = 1.9%), 99.4% (RSD = 1.7%), 97.9% (RSD = 1.2%), 96.7% (RSD = 2.5%) and 97.9% (RSD = 2.3%), respectively. The method is simple, accurate and reproducible for quality control of Poria.