Abstract: Residual lignin of unbleached kraft bamboo pulp, chlorine dioxide bleached and oxygen delignified pulps were analyzed by PyGC-MS. It was found that the thermal stability of residual lignin of chlorine dioxide bleached was higher than that of unbleached pulp and oxygen delignified pulp. The thermal stability of residual lignin of unbleached pulp was similar to that of oxygen delignified pulp. The structure of residual lignin was destroyed after chlorine dioxide bleaching and oxygen delignification, especially the residual lignin of oxygen delignified pulp. The charge of lower boiling fragments of residual lignin of oxygen delignified pulp was the highest.