The invention relates to a preparation technique of isosorbide, belonging to the technical field of pharmacy. In the preparation technique, solid sorbitol is used as the raw material, a mixture of perfluoro-sulfonic acid resin and palladium on carbon is used as the catalyst, and hydrogen is used as an anti-carbonation agent to prepare the non-carbonized light-colored isosorbide reaction liquid; and low-temperature concentration and solvent crystallization are utilized to substitute the original high-temperature distillation. The preparation technique comprises the following steps: dehydration reaction, neutralization decolorization, electrodialysis desalination, water removal by concentration, extraction crystallization, freeze-drying, and quality inspection and packaging (after the product is qualified in inspection, packaging, and warehousing as the finished product). The invention can prevent carbonization and prevent the reaction liquid from becoming dark, thereby enhancing the utilization ratio of the raw material; most calcium salts are precipitated due to low solubility, and the electric conductivity of the reaction liquid is low, thereby being beneficial to subsequent extraction; and the invention overcomes the defect of high energy consumption in the high-temperature distillation technique, and the quality of the prepared isosorbide is more excellent.