The invention discloses an oxygen-enriched combustion transformation method for a garbage incineration grate furnace. The method comprises the steps that an oxygen injecting step is added before the primary air of a combustion section, namely, oxygen obtained by gasifying and pressure regulating is injected into a primary air pipeline of the combustion section, so the air is fully mixed with the normal air of the combustion section and is then injected into a hearth; injection of normal secondary air is stopped, a draught fan behind a cloth bag deduster is connected with a secondary fan by a pipeline, so circulated smoke is guided into a secondary air pipeline by the secondary draught fan, and is injected into the hearth by a secondary air opening. The invention discloses a corresponding oxygen-enriched combustion device. The excess air coefficient is reduced, the flame temperature in the furnace is improved, the combustion condition is optimized, the generation of pollutants such as dioxin is effectively inhibited, the efficient, stable and safe operation of the incineration equipment is ensured, the smoke exhaust is reduced, the smoke heat loss and output of the draught fan are reduced, the combustion efficiency is improved, and the investment and operation cost of smoke purifying equipment are favorably reduced.