Abstract: To study the salt tolerance and salt tolerance mechanism of the seed of Agathis dammara,the germination experiment under salt stress was carried out in the laboratory of Xiamen Botanical Garden in 2022,and 9 NaCl mass fractions (0,0.3%,0.6%,0.9%,1.2%,1.5%,1.8%,2.4%,3%) were set up.The germination rate,germination index,vitality index,germ length,and the concentration of K⁺,Na⁺,Cl^-,MDA,SOD and POD were measured.The results showed that the threshold of salt tolerance was 1.27%,and the high salt concentration would inhibit seed germination and embryo growth.When the NaCl mass fraction was less than 1.5%,the harm of physiological drought was greater than that of ion toxicity,and the germination can be partially restored if fresh water was added in time.During germination,the endosperm absorbs salt ions from the environment,finally leaving the seedlings to reduce the salt concentration of the growth environment.At the same time,the seeds of A.dammara actively transport K⁺ to the embryo to help it maintain a high ratio of K⁺ to Na⁺,combined with the co-action of SOD and POD,to reduce the salt damage to the seed.In conclusion,the seed of A.dammara has a strong salt tolerance and can be sown on the saline-alkali soil in the coastal area of South China,where the soil salt content does not exceed 1.27%.