The invention provides a power protection control method for a hydraulic excavator. An operation rod instruction given by a driver is received, and flow instructions of hydraulic pumps on the excavator are correspondingly generated and converted into power requirements of the hydraulic pumps. The current real-time rotation speed of an engine is detected, and if the real-time rotation speed of the engine descends and is larger than the allowed value, the maximum available flow instruction of the hydraulic pumps is decreased, and the maximum available power of the corresponding hydraulic pump is decreased. Whether the required power of the hydraulic pumps is larger than the maximum available power of the hydraulic pump or not is judged, wherein if yes, the flow instruction of the hydraulic pump is worked out according to the maximum available power, and if not, an initially-generated flow instruction is executed. The power matching degree of the hydraulic pumps and the engine, the operating efficiency of a work device and the energy saving performance of the hydraulic excavator are improved, and the work device of the excavator runs more smoothly.