The invention relates to a dual-motor arrangement of a battery electric vehicle and a torque optimization method based on a convex optimization algorithm. The method comprises the following steps thatS1, according to a parameter of the vehicle, a longitudinal dynamics model is built; S2, a cyclic working condition of the vehicle is selected, according to the selected cyclic working condition, therequirement torque Tdem (k), requirement power Pdem (k) and biggest requirement torque Tdem, max and biggest requirement power Pdem and max of the vehicle are calculated; S3, under the premise that the capacity of a vehicle battery meets the power performance requirement, according to values of the Tdem, max and Pdex, and max, the motor size and battery size of the vehicle are selected; S4, the convex optimization processing is carried out on the motor and battery of the vehicle by the convex optimization algorithm; S5, the working state of each part of a vehicle transmission system is restricted; S6, a cost target function is determined. The method selects the dual-motor arrangement, the defect is made up that the work efficiency of the electric vehicle motor is low due to the single motor arrangement, the computing time of the optimization algorithm is quick, and the result is accurate.