Abstract: We studied the drought resistance of mycorrhizal Pinus massoniana caused by endogenous polyamines following a drought stress in the greenhouse with the treatment of DArg. The results showed that, in drought stress without treatment of DArg, the strength of drought resistance is in the order of P.massoniana inoculated by mixed fungi, inoculated by La and control plants. On the contrary, P.massoniana dealt with DArg and drought stress had taken place reversely. Mycorrhizal P.massoniana can maintain high content of Spm and high (Spd+Spm)/Put value, in which the biosynthetic of Put relies mainly on LArg precursor, and its conversion to Spm and Spd is more efficient. Based on the results, we conclude that ectomycorrhiza can adjust the biosynthetic and conversion of Put, alter the ratio of different polyamines, and then enhance the drought resistance of mycorrhizal P.massoniana.