The objective of the invention is to solve the problem of few researches on an effective and durable saline-alkali soil texture improvement method in the prior art. The invention provides an improvement method and an improvement agent for saline-alkali soil, and belongs to the technical field of saline-alkali soil improvement. According to the invention, through addition of iron mine tailings withdifferent addition amounts and different particle grades into to-be-improved saline-alkali soil, the iron mine tailings are utilized to change the proportion of sand, powder and clay particles in thesaline-alkali soil and reasonably adjust the constitution of texture, so the saline-alkali soil is improved into loamy soil; and by utilization of the irregular corrugated block structure of the ironmine tailings, a large number of capillary pores can be reserved, and a large number of non-capillary pores and large cracks can be constructed, so the permeability is improved; water drainage and salt leaching can be easily realized; capillary water can be hindered from rising; the accumulation of salts is reduced; the salt content of soil can be effectively reduced; and durable improvement of the saline-alkali soil and stability of soil texture are realized.