A production method of 3-chlorine-3'-ethyl-4, 4'-diamino diphenylmethane (CEMDA), which comprises preparing amine salt that adding water and hydrochloride into a reaction vessel, mixing and adding the anti oxidant of OCA, OEA and amine at 40-50DEG C, to obtain the water solution of amine salt, controlling temperature at 20-35DEG C, under the protection of nitrogen gas, mixing and adding formaldehyde in 2-3h, increasing temperature to 35-100DEGC, and reacting for 15-20h, thereby completely generating the addition compound of amine and formaldehyde, adding the compound into liquid alkali at 50-60DEG C until the pH value is 12, standing and separating the inorganic salt water solution at lower layer, distillating the organic layer in vacuum, and collecting the product at fraction section. The product is colorless or light yellow transparent liquid, the product content is higher than 91%, the yield is higher than 93%, the total effective amino content is higher than 96.00% and the pollutant discharge approaches to zero.