α-Fetoprotein (AFP) has a property to maintain the growth of hepetocellular cancinoma cells(HCC) in vivo, but the critical functional step of AFP is still obscurity. In order to explore AFP influences on the transduction of PTEN/AKT signal in HCC, expression of PTEN in human hepatoma cells and the effect of all trans retinoic acid (ATRA) on PTEN expression in these cancer cells were detected by Western blotting. AFP interacted with PTEN was analyzed by co-immunoprecipitation (Co-IP). Laser confocal microscopy was used to observe co-localization of AFP and PTEN. Short small RNA interfering (RNAi) was applied to knockdown the expression of AFP in Bel 7402 cells, and the phosphorylation of protein kinase B(AKT) was detected by Western blotting. Growth of Bel 7402 and HLE cells were assayed by MTT. Results showed that Bel 7402 cells expressed PTEN, and the expression of PTEN was induced by ATRA(160 μmol/L) mildly. Co-IP indicated that AFP has a property to interact with PTEN. PTEN co-localization with AFP was observed in cytoplasm of Bel 7402 cells. Constructed RNAi vector could knockdown the expression of AFP, expression of PTEN was promoted and phosphorylation of AKT was decreased when the expression of AFP was interfered or the cells were treated with ATRA(160 μmol/L). AFP-expressed vector pcDNA3.1-afp was transfected into human hepatoma HLE cells (AFP-non production). Co-IP analysis indicated that AFP interacted with PTEN, and expression of p-AKT(Ser473) was promoted in the tumor cells. It was also proved that pcDNA3.1-afp was able to reduce the role of Ly294002 in inhibiting the activity of AKT in HLE cells. These data provide the first evidence that AFP has a capacity to both interact with and inhibit activity of PTEN, which is also the pivotal events in the process that AFP activated the transduction of PI3K/AKT signal in hepatoma cells. Cytoplasmic AFP plays importance role on the resistance to ATRA induced apoptosis of HCC.