Abstract: The discoloration of Paulownia wood has been a serious problem in logs after felling and in lumber during storage and drying, which leads to considerable reduction with regard to utilization. The components responsible for the discoloration were extracted completely from the wood of Paulownia elongata S. Y. Hu with aqueous ethanol before discoloration. The extractive was separated into petroleum ether, chloroform, diethyl ether, ethyl acetate and water soluble fractions. Simulation tests of discoloration were conducted on filter paper and wood veneer with all of the fractions respectively. The results revealed that the water soluble fraction discolored seriously and is responsible for the color change of redish-brown. Color reactions of water soluble fraction indicated that leucoanthocyanins and proanthocyanins are the components responsible for the wood discoloration. Other factors affect wood discoloration were also discussed briefly.