This research was to investigate the performance of soft rot decay resistance, pH value change, and cell wall degradation after decay of Styrax tonkinensis wood with different heat treatments. Heat treatment was carried out under water vapor condition at different temperatures(170℃ to 210℃) and time( 2 to 6 h). The results showed with increasing the temperature and time could increase the resistance of soft rot decay . After the soft rot decay test, the weight loss ratio changed from 33.52% of the untreated wood to 1.60% of heat-treated wood at 210℃ for 6 h. The wood pH was influenced by soft rot decay. Usually, the wood pH increases (acidity decreases) along with soft-rot decay erosion. The pH of the untreated wood increases by 22.46% compared to the treated wood. The pH change rate of soft rot decay wood tends to decrease with an increase of heating temperature and time. The pH change rate of soft rot decay wood changed from 22.43% to 0.10% when the treatment changed from at 170℃ for 2 h to at 210℃ for 6 h and a similar trend was found for the rate ofweight loss. Invasion of the soft rot fungi caused the wood structure change and degrade the cell wall of Styrax tonkinensis, resulting in many V-type notches on the cell wall.