The utility model relates to a dual-unit field conversion control box, belonging to the technical field of motor conversion control devices, which adopts the technical proposal that the control box comprises a box body and a conversion control circuit arranged inside the box body. The conversion control circuit comprises two changer-over switches K1 and K2, which form a circuit for converting between a commonly used motor and a standby motor; two AC contactors C1 and C2 as well as the contacts C1-1 and C2-1 together form an actuating circuit for converting between the commonly used motor and the standby motor. While in use, only the cable of the prior motor is required to be connected into a conversion box, and two cables are led out of the conversion box; one cable is to be used by the commonly used motor, and the other cable is for the use of the standby motor; when conversion is necessary, the switch on the conversion box is shifted to the standby state, so as to realize the control over the standby motor without any other modification; therefore, the dual-unit field conversion control box has the advantages of simple structure, convenient manufacturing, less complexity of design and installation, lower investment, and simple yet reliable operations.