For the purpose of the quality control of Poria cocos, three major compounds were isolated and identified as pachymic acid (1), $3{eta}-hydroxylanosta-7,9(11),24-trien-21-oic$ acid (2), and dehydroeburicoic acid (3). The optimal extraction conditions for the quantification of pachymic acid its analogues were the 3 hours of reflux with 15g of P. cocos in 100ml 95% ethanol. HPLC conditions were as follows: Column; ZORBAX Eclipse XDB C18 $(4.6{ imes}250;mm,;Agillent)$, mobile phase; 1% HOAc in 70% $MeOH{ ightarrow}1%$ HOAc in 100% MeOH for 25 min, then 1% HOAc in 100% MeOH for 15 min, detector, ELSD, flow rate; 1ml/min. The mean contents of 1,2, and 3 in Poria cocos cultivated at 18 different site were $0.65{pm}0.19,;0.88{pm}0.72,;and;0.84{pm}0.54;mg/g$, respectively, and values might be the guide line for the quality control of P. cocos.