The invention provides a synthetic method of imidacloprid, which comprises the following steps: by using 2-chloro-5-chloromethylpyridine, ethylenediamine and guanidine nitrate as raw materials, carrying out aminating, cyclizing, dehydrating and the like to synthesize imidacloprid. According to the method, the safety problem caused by generation of unstable nitroguanidine in the reaction process isavoided, the production process is high in safety, the product purity is good, the yield is high, and industrialization is easy to realize.