The invention provides a preparation method for 3-aminomethyl-3,5,5-trimethylcyclohexyl amine. According to the preparation method, imidization reaction materials containing 3-cyano-3,5,5-trimethylcyclohexyl imine is subjected to first-stage hydrogenation reaction under the help of a cycled material of a subsequent step, so that a first hydrogenation reaction material is obtained, and also generation of HCN-removed products is effectively inhibited, then a second-stage hydrogenation reaction is performed under the effect of a heating-degradable alkali auxiliary agent, then heating is performed to decompose the alkali auxiliary agent, a part of degraded materials is taken as the cycled material and is returned to the first-stage hydrogenation reaction as an auxiliary agent, and the residual part is subjected to third-stage hydrogenation reaction, so that 3-aminomethyl-3,5,5-trimethylcyclohexyl amine is obtained, and the content of 3-cyano-3,5,5-trimethylcyclohexyl amine and secondary amine products is effectively reduced.