In our experiments, Syrian hamaster embryo cells (SHE) exposed to ,238,Pu ,α, particles acted as the target cells, the transformed frequency (TF) was determined by means of 10 days colony formation assay for appraising the promoting effect of recombinant human tumor necrosis factor ,α, (rhTNF-α) . Different passage cells were achived by a series of passaging experiments, and their growth kinetics, anchorage independence growth nature and tumorigeniciey in nude mice were analysed. The results showed that (1) rhTNF-α could increased the TF of primary SHE cells previously irradiated by ,α, 0.5Gy dose of ,α, particles by a factor of two; (2) addition of rhTNF-α to subcultures of irradeated SHE cells permitted the continuous propagation of primary cells up to the both passages; (3) cells from 40th passage sustained growth under low serum condition; and (4) the monoclonal cells Tc, Td and cells of 40th passage were tested for their tumorigenicity in nude mice, and poorly differentiated fibrosarcoma were founed in two out of three nude mice in each group.