Abstract: The growth change of two years old Pinus sylvestriformis seedling under salt (NaCl袁Na2CO3) stress of different concentration and ratio was observed in pots containing soil. The results showed that with the increase of salt concentration, the plant height and stem diameter were obviously restrained. Furthermore, the single salt stress of NaCl was significantly stronger than Na2CO3, while the inhibition of complex sodium salt to the plant height was also related to salt proportion. In addition, the damage of NaCl to the plant was significantly serious than Na2CO3 and complex sodium salt. With the increase of Na2CO3 concentration (or the decrease of NaCl concentration), the stress of complex sodium salt to seedlings was firstly weakened and then strengthened. According to the related definition of salt tolerance, the salt tolerance threshold of P. sylvestriformis seedling was approximately 4.5 g/kg.