The invention relates to a method of diabecron, using dimethylamine aqueous solution of 40% concentration one value, dropping hydrochloric acid in dimethylamine aqueous solution until the PH value is 2, stopping drop acid, vacuum concentrating solution, cooling to 50deg C after there is crystal in reactor, adding ethanol 0.3 shares, dicyandiamide 0.62-0.67 shares, heating to 80deg C,doing vacuum distillation to distill ethanol, reacting to produce diabecron when heating to 130deg C, adding ethanol 2-3 shares when cooling to 50deg C, discharging when cooling to 5deg C, centrifugal rinsing and drying, drying, recovering ethanol, getting diabecron crude product, drying crude product, adding deionized water 2.5-3 shares, activated char 0.02 shares, ethylene diamine tetraacetic acid disodium 0.003 shares, heating-up to 75-80deg C, cooling to 50deg C again after agitating, adsorbing, filtering, concentrating, adding ethanol 2 shares and agitating, cooling to 5deg C, discharging and centrifugal rinsing and drying, drying to recover the ethanol, getting diabecron completed product, on-spec product's yield of this invention is 75% -80%,the cost is decreased 15%-25% compared with primal method, hasing advantages of high product yield and low cost.