The present invention relates to an OBC module assembly for an electric vehicle having an improved heat-dissipation efficiency. The OBC module assembly for an electric vehicle is for charging a battery for an electric vehicle, and comprises an OBC housing, a heat-dissipation pad, an inductor case and a moulding part. The OBC housing has a PCB substrate mounted therein. The heat-dissipation pad is placed in a lower end inside the OBC housing. The inductor is placed in an upper part of the heat-dissipation pad, is composed of a core and a coil wound around the core, and is thereby electrically connected to the PCB substrate. The inductor case is formed to have an opened lower part for wrapping the inductor in an upper part thereof, and a moulding material injection hole for dissipating heat of the inductor arranged in an upper end thereof. Regarding the moulding part, the moulding material is injected and filled inside the inductor case through the moulding material injection hole.