Abstract: To study the effects of crude polysaccharides from Poria cocos (PCCP) on proliferation and differentiation of 3T3-L1 preadipocyte. 3T3-L1 cells were treated with culture medium contained different concentrations of PCCP (0, 50, 100 and 200 μg mL-1) for 48 h and subsequently cell proliferation was assayed by MTT Method. The extent of the differentiation was determined by fluescence spectrophotometry and Oil Red O staining on days 8 after treatment with culture medium supplemented with different concentration PCCP (0, 50, 100 and 200 μg mL-1). As the results, the different concentration PCCP (50, 100 and 200 μg mL-1) inhibited to some extent proliferation of 3T3-L1 preadipocytes when compared with the control. But the difference is not significant (p>0.05). And PCCP stimulated cell differentiation into adipocyte at lower concentration (50 and 100 μg mL-1) (p<0.05) while it inhibited cell differentiation into adipocyte at high concentration (200 μg mL-1) (p>0.05). It can be concluded from the results that the PCCP was involved in regulation of adipogenesis and lipogenesis.