A control system of a hybrid electrical vehicle includes: a transmission device; an engine power subsystem and a motor power subsystem connected with the transmission device; and a control module configured to control the hybrid electrical vehicle to operate in a hybrid electrical-economical mode by controlling the engine power subsystem and the motor power subsystem, and to control the hybrid electrical vehicle to operate in a first manner if a current slope detected by the hybrid electrical vehicle is less than or equal to a minimum slope and a current electric quantity of a power battery of the motor power subsystem is less than or equal to a first electric quantity threshold, or if the current slope is less than or equal to the minimum slope and a maximum allowable discharge power of the power battery is less than or equal to a first power threshold.