The invention relates to a synthesis method of epichlorohydrin, which is a reclaim utilization method of R-3-chloro-1, 2-propanediol during the separation and the preparation of S-epichlorohydrin by utilizing the dynamics of epichlorohydrin and a utilization method of utilizing glycerin which is the byproduct in the production of biodiesel. The R-3-chloro-1, 2-propanediol is reacted with chlorinating agent with the catalysis of the acid catalyst to generate the 1, 3-dichloro propanol, the obtained 1,3-dichloro propanol is reacted with alkali to generate the epichlorohydrin; the glycerin is reacted with the chlorinating agent with the catalysis of the acid catalyst to generate the 1,3-dichloro propanol, and the obtained 1,3-dichloro propanol is reacted with alkali to generate the epichlorohydrin. The synthesis method of the invention is simple, which can effectively convert the highly toxic waste R-3-chloro-1, 2-propanediol and the crude glycerin into the epichlorohydrin, the yield is high, the production cost is low, the environment pollution is reduced, so the synthesis method is an ideal method for industrialization reclaiming and utilization of R-3-chloro-1, 2-propanediol and the crude glycerin.