RT-PCR,Oil red O staining, Oil red O staining extract and spectrometer were used to study the effect and mechanisms of different concentrations of 9-cis RA (0-10 micromol/L) on the differentiation of pig primary preadipocyte. The results showed that different concentrations of 9-cis RA had different effect on the differentiation of preadipocyte. Low concentrations of 9-cisRA (0-10 nmol/L) could promote the differentiation of preadipocyte and upregulate the expression of RXRalpha, PPARgamma mRNA and the activity of GPDH. High concentrations of 9-cisRA (100 nmol/L-10 micromol/L) could inhibit the differentiation of preadipocyte and downregulate the RXRalpha, PPARgamma mRNA and the activity of GPDH. These results showed that different concentrations of 9-cis RA could promote or inhibit the differentiation of pig preadipocyting by regulating the expressions of RXRalpha and PPARgamma.