Abstract-The addition reaction was carried out under the acidic conditions using dicyandiamide and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (DMDC) as raw materials to prepare 3,3'-dimethyl P-guanidino) dicyclohexylmethane. The effects of reaction temperature, reaction time and molar ratio of materials on the yield of the product were discussed. The products were characterized by IR spectra and NMR spectra. The results showed that the optimum reaction conditions were as follows: reaction temperature 130 °C, reaction time 9 h, the optimum acidity is concentrated hydrochloric acid in an amount of 1:1.1, n (DMDC): n (Dicyandiamide) = 1:2. Under these conditions, the yield of crude product was 81.3%.