The invention discloses an internal high pressure forming device for manufacturing a special-shaped interface pipe for a vehicle. The internal high pressure forming device comprises an upper template,an upper main mold, a lower template and a lower main mold; the upper main mold is fixed on the upper template, the lower main mold is fixed on the lower template, an upper main mold cavity is formedin the upper main mold, and the lower main mold is provided with a lower main mold cavity; the upper template and the lower template are provided with detachable auxiliary molds respectively, the auxiliary molds are provided with auxiliary mold cavities, the auxiliary cavities are located at one ends of the auxiliary molds on the upper template and abut against the upper main mold, and the auxiliary mold cavities on the upper template and the upper main mold cavity form an upper mold cavity. The upper mold and the lower mold are divided into the upper main mold, the auxiliary molds, the lowermain mold and the auxiliary molds, and expansion deformation parts, namely the parts for plastic deformation, are arranged in the upper main mold cavity and the lower main mold cavity, and other material supplementing parts are arranged in the auxiliary mold cavities, so that when the shapes of the material supplementing parts of the pipe change, only the auxiliary molds need to be replaced, other parts in the device do not need to be replaced, the number of molds is reduced, and the cost of the device is reduced.