Purifying method for engine cylinder

The invention discloses a purifying method (900) for an engine cylinder. The purifying method includes the following steps that 901, high-viscosity olein and an oxyhydrogen supplying machine are provided; 902, the high-viscosity olein is poured into an engine, and the cylinder is protected in advance; 903, a gas outlet pipe of the oxyhydrogen supplying machine is guided into a gas inlet of the engine; 904, the oxyhydrogen supplying machine and the engine are started, and therefore hydrogen and oxygen which are generated by the oxyhydrogen supplying machine can enter the engine to be combusted together with fuel; 905, idle running of the engine is maintained for a period of preset time, the preset time is not shorter than 15 min, the carbon deposit in the cylinder is carbonized and volatilized to be discharged out through high-temperature combustion under complete combustion of the fuel, and the effect of cleaning and purifying the engine is achieved; and 906, the oxyhydrogen supplying machine and the engine a