N-methyl pyrrolidone,hydrochloric acid and thiourea dioxide were adopted as the raw material,and 4-methyl guanidine butyric acid was synthesized through two-step reaction.The optimum synthesis condition for the first step was as follows：n（N-methyl pyrrolidone）∶n（10% HCl）= 1∶2.0,reaction temperature 135 ℃,reaction time 5 h;at that moment,the yield of intermediate 4-methyl-amino butyric acid hydrochloride was 72.89%.The optimum synthesis condition for the second step was as follows：n（4-methyl-amino butyric acid hydrochloride）∶n（thiourea dioxide）= 1∶2.0,reaction temperature 25 ℃,reaction time 12 h,at that moment,the yield of target product was 82.68%.Structure characterization on the intermediates and the target products were carried out through Fourier transform infrared spectroscopy and elemental analysis.
