The invention discloses a vehicle control unit shell based on an external cooling device. The vehicle control unit shell comprises an upper shell, a lower shell and the external cooling device. The left side and the right side of the top end face of the upper shell are symmetrically provided with multiple pairs of installation cavities. Installation through holes are formed in the bottom walls of the installation cavities. A plurality of cooling fins are evenly embedded in the top end face of the upper shell. The external cooling device is arranged on one end side of the upper shell and comprises a ventilation cylinder, an air suction fan and a dustproof net. The air suction fan and the dustproof net are arranged in the ventilation cylinder. A plurality of installation blind holes matched with installation vent holes are evenly formed in the top end face of the lower shell. An installation substrate is arranged in an inner cavity of the lower shell. Lots of heat generated when an electrical element on the installation substrate works is transmitted to a second supporting plate through a first supporting plate and a cooling rod to be dissipated; the shell is directly connected with the installation substrate, is rapid in cooling speed and can bring away heat on the installation substrate in time, and it can be effectively avoided that heat is accumulated on the installation substrate and the electrical element is burnt out.