The effects of 2 species AM fungi (G.mosseae,G.versiforme) on salt tolerance of processing tomato were studied in pot culture under different NaCl concentrations (0,50 and 85 mmol/L).The results showed that:(1)Under 0 mmol/L NaCl conditions,compared with non-mycorrhizal plant,mycorrhizal plant can enhance root activity,promote the accumulation of soluble sugar,soluble protein in leaves and proline content in roots,promote SOD and POD activities in leaves and reduce accumulation of MDA content,but no significant difference.(2)Under 50 mmol/L and 85 mmol/L NaCl stress,compared with non-mycorrhizal plant,mycorrhizal plant significantly enhanced root activity,promoted the accumulation of soluble sugar,soluble protein in leaves and proline content in roots,promoted SOD and POD activities in leaves and reduced accumulation of MDA content.(3)Expression of H⁺-PPase (AVP1) gene was studied by qRT-PCR and it was regulated by AMF and salt stress jointly.With the increasing of the concentration of salt,the AVP1 gene expression decreased.AVP1 gene expression of mycorrhizal plant is higher than that in non-mycorrhizal plant distinctly.We concluded that inoculation G.mosseae and G.versiforme to processing tomato can enhance the seedlings osmotic adjustment mechanism of salt tolerance,raise the activities of antioxidant and AVP1 gene expression.So the damage of salt stress on the plant would be alleviated and the adapt ablity of processing tomato seedlings to salt environment would be improved.