The invention discloses a synthesis method of an N-substituted hydantoin compound, which comprises the following steps: by using an acyl azide compound as shown in formula I and a glycine ethyl estercompound as shown in formula II as raw materials, carrying out heating reaction in the presence of an additive to obtain the N-substituted hydantoin compound as shown in formula III, wherein the reaction equation is shown as the specification; in the equation, R1 and R2 are independently selected from alkyl, substituted alkyl, aryl, substituted aryl or aromatic heteroradical, the R2 is selected from alkyl or aryl, and R3 is selected from a hydrogen atom and a hydrocarbyl group. The synthesis method can efficiently synthesize the functionalized N-substituted hydantoin compound, has the advantages of few synthesis steps, mild conditions, safe operation, nontoxic, cheap and easily available raw materials, good compatibility with functional groups and high atom economy, can obtain the N-substituted hydantoin compound with a novel structure and a nitrogen-containing heterocyclic skeleton, and has the yield of 92% and the purity of 99% , and the industrial synthesis is easy.