The invention discloses a two-step mode two-temperature transient liquid-phase bonding method for dissimilar metals, wherein the eutectic temperature between an intermediate layer and high-melting point parent metal is 100-400 DEG C higher than that between the intermediate layer and low-melting point parent metal. The method comprises the following steps of: (1) welding one end of the intermediate layer to the high-melting point parent metal at the temperature T1 by using a transient liquid phase bonding method; and (2) welding the other end of the intermediate layer to the low-melting pointparent metal at the temperature T2, wherein the temperature T2 is lower than the melting temperature of the low-melting point parent metal. The two-step mode two-temperature transient liquid-phase bonding method for the dissimilar metals disclosed by the invention can be used for bonding between the dissimilar metals with significant difference for physical, chemical and metallurgical properties,in particular for bonding between the dissimilar metals with a melting point difference value of 300-700 DEG C, the bonding and the sufficient diffusion between the high-melting point parent metal and the intermediate layer are ensured to be realized, and meanwhile, the occurrence of melting and burning loss of the parent metal with a lower melting point in a welding process can be prevented, so that the effective bonding between dissimilar metal weldments is realized.