The application provides a water-cooled heat dissipation vehicle-mounted device and an
electric vehicle. The shell of the vehicle-mounted device comprises an integrated shell, and the integrated shell comprises an electrical
accommodation groove and an internal water
inlet channel. The electrical
accommodation groove is used for accommodating an integrated support and a first circuit board. The first circuit board is used for bearing electrical components of at least one of a vehicle-mounted charger or a
motor controller. The integrated support is arranged between the first circuit board and the groove bottom of the electrical
accommodation groove. The integrated support comprises a support waterway inlet and at least one radiator waterway interface. The support waterway inlet is used for receiving cooling water output by the outlet of the internal water
inlet channel. Each radiator waterway interface is used for conveying cooling liquid to at least one of a water-cooled radiator of the vehicle-mounted charger or a water-cooled radiator of the
motor controller. The integrated support is used for connecting the water-cooled radiator of the vehicle-mounted charger and the water-cooled radiator of the
motor controller with the internal water
inlet channel of the integrated shell, so that the
cooling efficiency of the vehicle-mounted device is improved and the volume is small.