The invention provides an automobile hydrogen and oxygen economizer and a control method thereof. The automobile hydrogen and oxygen economizer structurally comprises a shell, a reaction kettle and a filter kettle, wherein the shell structurally comprises a lower shell, a middle frame and a top cover, the middle frame is buckled on the top of the lower shell, the top cover is installed on the top of the middle frame through a hinge, additionally, a sealing cover which is used for protecting electric appliances of a control device is arranged in the shell, the reaction kettle is installed in the lower shell, and the filter kettle is installed on the top of the middle frame. The invention provides a vehicle-mounted hydrogen and oxygen generation system, the generation of hydrogen and oxygen along with an automobile is realized, after hydrogen and oxygen are led to an engine, the in-cylinder combustion is improved, the engine power is increased, the fuel consumption is reduced, the fuel saving effect is achieved, and additionally, harmful gas in tail gas is reduced. The system has the advantages of small size, light weight, high efficiency, low cost and easiness in control.