Abstract: Abscisic acid (ABA) is an endogenous hormone of higher plants and an important composition of the wounding message. Using GC/MS technique, the ABA content was analyzed in undamaged, insect-damaged and intact leaves of Pinus massoniana in Jiangxi Province at different time in 2004 and 2005.Results showed that, compared with the control, although the content of ABA increased after ID 1 h, its peak was after ID 72 h and the content of ABA increased by 53.14% and 15.85%, respectively.The ABA content of intact leaves was also higher than that of the control.It would be concluded that the defensive system of P.massoniana was started up when it was damaged and also, resistance of the neighboring healthy twigs was induced.