The invention discloses a novel method for synthesizing 4,6-dichloro-2-(propylthio)-5-aminopyrimidine (I), namely an important intermediate of ticagrelor. The method comprises the following steps: carrying out a condensation reaction between substituted aminomalonic acid diethyl ester (III) and urea to generate 2,4,6-trihydroxy-5-substituted aminopyrimidine (IV); conducting chlorination on the obtained compound 2,4,6-trihydroxy-5-substituted aminopyrimidine (IV), to obtain 2,4,6-trichloro-5-aminopyrimidine (V); carrying out a reaction between the obtained compound 2,4,6-trichloro-5-aminopyrimidine (V), and propanethiol to generate 4,6-dichloro-2-(propylthio)-5-aminopyrimidine (I). The synthetic route adopted in the method is low in cost, simple to operate, and suitable for industrial production.