Preparation method of 3-chloro-1,2-propanediol

The invention discloses a preparation method of 3-chloro-1,2-propanediol. The preparation method comprises the following steps that (1) raw materials composed of chloropropylene oxide, deionized water and a cation resin are adopted and 20 to 30 wt% of the raw materials are mixed with stirring, wherein a weight ratio of chloropropylene oxide, deionized water and the cation resin is (550 to 650): (250 to 350): (1.5 to 2.5); the mixture is heated to a temperature in a range of 70 to 75 DEG C in a time period of 30 to 60 minutes; the rest of deionized water is added uniformly into the mixture at an initial temperature of 80 to 90 DEG C in a time period of 2 to 3 hours to cause a hydrolysis reaction; and the hydrolysis reaction lasts for 1 to 2 hours after all deionized water is added; and (2)hydrolysate obtained form the step 1 is filtered and is fed into a distillation still to be distilled and a 3-chloro-1,2-propanediol product is obtained at a gas phase temperature equal or greater than 82 DEG C and a vacuum degree equal or greater than 0.098 MPa. The preparation method adopts a cation resin as a catalyst, can realize complete hydrolysis of chloropropylene oxide, and has the characteristics of high conversion rate, high product purity, short production period and low production cost.