The invention discloses an alkaline soil alkali-digesting, improving and plant growth promoting method. The alkaline soil alkali-digesting, improving and plant growth promoting method comprises the following steps that 1, initial alkali digestion is performed, standing straw in alkaline soil is cut into smashed straw and laid on the earth's surface after crop harvesting, and urea phosphate is sprayed; 2, drip washing is performed, rotary tillage and flatting are performed on the earth's surface of the alkaline soil to obtain a plough layer, the plough layer is irrigated, and salt and alkali drip washing is perform to a subsoil layer of the plough layer; 3, mulching film laying, drop irrigation and sowing are performed, wherein a mulching film is laid on the alkaline soil surface, and crops are sowed by punching the surface of the plastic mulching film or before the plastic mulching film is laid; 4, alkali digestion and fertilization are performed in a growth period, an alkali-digesting agent for alkaline soil is drop-irrigated in the growth period of the crops, and alkali digestion and improvement of alkaline soil are achieved. By the adoption of the alkaline soil alkali-digesting, improving and plant growth promoting method, the alkaline soil can be remarkably improved in a long-acting mode, a relatively ideal growth environment can be also rapidly created for crop root system in a short time, accordingly an alkaline soil improving period is effectively shortened, and alkaline soil improving efficiency is improved.