Abstract: The present invention provides reconstituted tobacco and a preparation method thereof, and belongs to the technical field of tobacco. The preparation method provided by the present invention includes the steps of: subjecting tobacco stems to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp; mixing the tobacco stem pulp with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, where the alkaline matter includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate; mixing the oxygen-delignified tobacco stem pulp with tobacco pulp, calcium carbonate and a retention agent, and subjecting the mixture to a papermaking process in the paper machine to obtain reconstituted tobacco sheets; and coating the reconstituted tobacco sheets with a concentrated tobacco extracting solution to obtain reconstituted tobacco.