The invention relates to a new synthetic process of L-pyrrolidone carboxylic acid. The process comprises the steps of adding an organic solvent and L-glutamic acid into a reactor, heating to 50-60 DEG C, stirring, dropping a dehydrating agent, performing heat preservation reaction for 1-5 hours, then naturally cooling, performing after-treatment on a product, and performing vacuum drying to obtain a white solid product. Under the condition of normal pressure and in presence of the dehydrating agent, a technical scheme of synthesizing L-pyrrolidone carboxylic acid at relatively low temperature is provided; the technical scheme is mild in synthesis condition, short in reaction time, convenient in production operation and simple in equipment requirement; L-pyrrolidone carboxylic acid obtained by adopting the technical scheme is relatively high in product purity, and is beneficial for industrial production.