Preparation methods of methyl-d3-amine and salts thereof are provided, which contain the following steps: (i) nitromethane is subjected to react with deuterium oxide in the present of bases and phase-transfer catalysts to form nitromethane-d3, which is subsequently subjected to reduction in an inert solvent to form methyl-d3-amine, and optionally, methyl-d3-amine reacts subsequently with acids to form salts of methyl-d3-amine; or (ii) N-(1,1,1-trideuteriomethyl)phthalimide is subjected to react with acids to form salts of methyl-d3-amine. The present methods are easy, high efficient, and low cost.