The invention discloses a method for improving the northeast black soil fertility. The method includes the following steps that 1) northeast black soil is deeply loosened, and is deeply loosened one time every three years; 2) straw is smashed, then a straw decomposing agent is applied, and after corn is harvested, straw is smashed, turned, pressed and returned to a field; 3) after straw is returned to the field, suppressing and ridging are carried out; 4) 220 kg.hm<-2>-250 kg.hm<-2> of nitrogenous fertilizer (N), 110 kg.hm<-2>-135 kg.hm<-2> of phosphatic fertilizer (P2O5) and 100 kg.hm<-2> ofpotash fertilizer (K2O) are basically applied, and are subjected to even furrow application. According to the method, through comprehensive application of multiple technical measures such as deep loosening, straw field returning and accurate fertilizer applying, the defects that straw field returning of northeast black soil regions is not suitable for decomposition, and the influence on seeding ofnext-stubble crops is generated are effectively overcome; the soil organic matter content can be effectively increased, the soil structure is improved, and the culture fertility is achieved; meanwhile, the crop yield is kept, it is achieved that the win-win aim that the crop yield is continuously kept, and the soil fertility is improved is achieved, and the method is suitable for northeast regions with the accumulated temperature of 2,500 DEG C or above.