The invention relates to the technical field of severe saline-alkali soil greening, in particular to a method suitable for directly planting macrophanerophyte in natural soil of coast silt severe saline-alkali soil of which 1 m soil body contains more than 2.0 percent of total salt. The method comprises the following steps: building a burrock-type platform field through drainage trenching; paving a water supplying pipeline; broadcasting phosphogypsum and humic acid; then broadcasting semi-decomposed maize straw manure for soil amelioration; conducting mechanical deep tillage and land leveling; paving water seepage pipes; leaching salt through fresh water; electing a macrophanerophyte type; planting. According to the invention, the physical chemical property of the soil is improved through 'soil amelioration, fertilization and deep tillage', so that soil leaching is accelerated while the soil is fertilized. Therefore, a soil ecological environment suitable for tree growth is formed gradually, and lasting greening is further realized. Compared with the greening method in which the ground is elevated through soil dressing, the method has the advantages that cost is reduced; the macrophanerophyte survival rate is higher than 95 percent; low-cost lasting greening of severe saline-alkali soil is realized in very deed; the economic benefit and ecologic landscape of severe saline-alkali soil greening are improved remarkably.