[Objective] Studing the amelioration effect of different soil amendments that are potentially suitable for costal heavy saline-alkali soil.[Methods] Hekang, phosphogypsum, micro-organism fertilizer, Tusheng, officinal-fertilizer and organic manure were used to amend saline and alkali soil in Maotuo field experiment station of Yellow River Delta. The effects of soil amendments on physiochemical and biological characteristics of costal strongly salinized soil were studied.[Results] (1) The results showed that the soil bulk density decreased and the aeration decreased when the soil amendments were added, among which phosphogypsum and Hekang had good amelioration effects; (2) Electric conductivity of soil was observed obviously decreased when each of the amendments added with a 15.9% or over decrease. The salty effect of saline and alkali on soil could be mitigated with soil amendments, especially with cotton field; (3) The phosphogypsum and Hekang was better than others in mitigating salt and modifying soil chemical properties; (4) Moreover, the microbial biomass and soil respiration increased with the addition of soil amendments, especially with the additions of organic manure or micro-organism fertilizer treatments; (5) Soil fertility and cotton production could increase by organic manure or micro-organism fertilizer treatments.[Conclusion] The physiochemical and biological characteristics of saline alkali soil can be improved with Hekang, phosphogypsum, micro-organism fertilizer, and organic manure amendments.