A preparation method of a cross-linked sodium hyaluronate gel is disclosed, which including: preparing an alkaline aqueous solution of hyaluronic acid: formulating a sodium hyaluronate alkali liquor with the concentration of 10-30% g/ml; and carrying out a cross-linking reaction: the cross-linking agent used in the cross-linking reaction being divinyl sulfone or 1,4-butanediol diglycidyl ether, the cross-linking reaction being carried out in an alkaline aqueous solution of hyaluronic acid, the reaction temperature of the cross-linking reaction being 20-40° C., the time of the cross-linking reaction being 4-8 h, and the like. The method of this invention has many advantages, such as easily available raw materials, mild reaction conditions, high cross-linking efficiency, simple process and post-treatment, and easy operation. The obtained cross-linked sodium hyaluronate has a three-dimensional network structure by the crosslinking reaction with good mechanical properties, and can be used as a good drug carrier and a tissue engineering scaffold material.