The invention discloses a hybrid power control method, a hybrid power control device and a power system. The device comprises a battery information acquisition module and a motor control module, wherein the battery information acquisition module is used for acquiring and obtaining the stress optical coefficient (SOC) value of a battery; and the motor control module is used for controlling connection or disconnection of a motor and an external power supply according to the obtained SOC value of the battery, so that the external power supply is used for supplying power to the motor when the electric quantity of the battery of the motor is insufficient. According to the technical scheme, the operations of an engine and the motor of construction machinery can be effectively controlled, stable and continuous operation of the construction machinery is ensured, and the problem of discontinuous construction of the construction machinery due to inconvenient addition of fuel oil in the prior art is solved.