Low-temperature operation control method of engine and low-temperature operation control system of engine

The invention provides a low-temperature operation control method of an engine and a low-temperature operation control system of the engine. The method comprises the steps that under the condition of engine cold start, the temperature of cooling liquid at an outlet of a power battery is obtained, a first temperature is obtained, the temperature of cooling liquid in a large circulation loop of a fuel cell engine is obtained, and a second temperature is obtained, and the power battery is connected with the fuel cell engine; under the condition that the first temperature is larger than the second temperature, the large circulation loop is heated through the power battery until the first temperature is smaller than or equal to the second temperature, and the engine is controlled to enter a cold start protection mode; and in the cold start protection mode, the large circulation loop is heated through the air compressor and the power battery until the second temperature is larger than or equal to the preset tempera