The invention relates to a slow-release salt inhibiting fertilizer for saline and alkaline land and a preparing method of the slow-release salt inhibiting fertilizer for saline and alkaline land. The slow-release salt inhibiting fertilizer for saline and alkaline land comprises, by weight, 20-30 parts of nitrogenous fertilizer, 5-10 parts of chitosan, 5-10 parts of sodium alga acid, 10-20 parts of potassium humate, 10-20 parts of phosphatic fertilizer, 5-10 parts of potash fertilizer and 2-5 parts of glycerinum. According to the slow-release salt inhibiting fertilizer for saline and alkaline land and the preparing method of the slow-release salt inhibiting fertilizer for saline and alkaline land, the chitosan, the sodium alga acid, the potassium humate and the glycerinum are mixed to serve as wrapping materials and are placed in a roller granulator together with the nitrogenous fertilizer, drying and cooling are conducted after even coating is completed, and then the mixture is mixed with the phosphatic fertilizer and the potash fertilizer evenly, so that the slow-release salt inhibiting fertilizer for saline and alkaline land is obtained. According to the slow-release salt inhibiting fertilizer for saline and alkaline land, the slow release effect is good, the content of salt in soil can be reduced, the volume weight of soil can also be reduced, the content of organic matter in soil is increased, the crop yield is increased, and then improvement and sustainable utilization of saline and alkaline land are achieved.