The authors investigated changes in Betula costata’s color under different heat-treatment conditions using ultraviolet visible spectroscopy.The results showed the temperature and heat treatment duration were the two major factors for wood discoloration.The authors also observed that the Betula costata（ΔE*） color difference increased,which caused the treated lumber color to become redder and darker,with increasing temperature and duration.They also noted that the oxidized phenolic hydroxyl group could cause wood discoloration.