An electric assembly for a vehicle, comprising: a box assembly, wherein a mounting plate is disposed in the box assembly, the mounting plate divides a space within the box assembly into a motor holding cavity and a transmission holding cavity that are arranged along an axial direction of a motor shaft, and the mounting plate has a shaft via-hole making the motor holding cavity and the transmission holding cavity be in communication with each other; a motor, wherein the motor is disposed in the motor holding cavity; and a transmission, wherein the transmission is disposed in the transmission holding cavity, and the motor is power-coupled to the transmission, wherein the box assembly comprises a transmission box and a motor box, the transmission box comprises a front box and a rear box, the motor box comprises a motor housing and a motor backend cover, the front box and the motor housing are disposed adjacent to each other, and the mounting plate is constructed as a part of the front box or a part of the motor housing, characterized in that the front box and the motor housing are integrally formed, and in that one or more of a first connection rib, a second connection rib and a third connection rib are connected between an outer surface of the front box and an outer surface of the motor housing, the first connection rib is connected between an upper end face of the motor housing and an upper end face of the front box, the second connection rib is connected between a lower end face of the motor housing and a lower end face of the front box, and the third connection rib is located between the first connection rib and the second connection rib. a box assembly, wherein a mounting plate is disposed in the box assembly, the mounting plate divides a space within the box assembly into a motor holding cavity and a transmission holding cavity that are arranged along an axial direction of a motor shaft, and the mounting plate has a shaft via-hole making the motor holding cavity and the transmission holding cavity be in communication with each other; a motor, wherein the motor is disposed in the motor holding cavity; and a transmission, wherein the transmission is disposed in the transmission holding cavity, and the motor is power-coupled to the transmission, wherein the box assembly comprises a transmission box and a motor box, the transmission box comprises a front box and a rear box, the motor box comprises a motor housing and a motor backend cover, the front box and the motor housing are disposed adjacent to each other, and the mounting plate is constructed as a part of the front box or a part of the motor housing, characterized in that the front box and the motor housing are integrally formed, and in that one or more of a first connection rib, a second connection rib and a third connection rib are connected between an outer surface of the front box and an outer surface of the motor housing, the first connection rib is connected between an upper end face of the motor housing and an upper end face of the front box, the second connection rib is connected between a lower end face of the motor housing and a lower end face of the front box, and the third connection rib is located between the first connection rib and the second connection rib.