Abstract: The sodium pump activity of tumor cells and effect of Oridonin (Grid.) were measured by using ⁸⁶Rb trancing method. The results showed that serum stimulus increased pump activity of EAC cell in vitro;while Orid inhibited the ⁸⁶Rb infulx of EAC cell in vitro (1-7.5ug/ml) and in vivo (5-20mg/(kg·d) × 3). preincubating cell with Orid (5ug/ml) for 1, 3, 6, 9h, the inhibitory rates were 22%, 39%, 50%, 63%, respectively. The pump activity of tumor cell lines 7901, Hep-2 and normal cell line SL were 4255, 4681 and 2632; the inhibitiry rates of Orid. (5ug/ml) were 42%, 51% and 20% separately. These data suggested that Orid. can restrain tumor cell growth by means of inhibiting sodium pump activity.