The invention provides a four-stroke spark ignition type hydrogen-oxygen engine and a control method, and particularly relates to a hydrogen and oxygen supply system and oxygen injection and combustion process control of the four-stroke spark ignition type hydrogen-oxygen engine. According to the system, on the basis of keeping main components of an original engine, an electronic control unit (4),an oxygen tank (6) and an oxygen nozzle (9) are additionally mounted. The electronic control unit (4) can calculate the injection pulse width, the injection phase position, the number of times of injection and the ignition angle of the oxygen nozzle according to a needed power signal (c), and therefore the engine can control oxygen to be injected into a cylinder to form layered mixed gas layeredbased on an oxidization agent, the output power can be controlled by adjusting the injection pulse width of the oxygen nozzle, then the opening degree of an electric control throttle can be increasedto the greatest extent so as to reduce gas injection losses, and the effective efficiency can be improved. According to the system, the oxygen in-cylinder direct injection technology is adopted, and the tempering hidden danger brought by pre-mixing outside a hydrogen cylinder and the oxygen cylinder is avoided.