Abstract: In order to investigate the fiber structure, textural porosity and their influences on combustion property of paper-making process reconstituted tobacco, the morphology and distribution of fiber in reconstituted tobacco were analyzed by a fiber tester, and the microstructure of fibers, tobacco stem vessels and pulp stacking stratifications were observed and compared with scanning electron microscope (SEM). The differences in physical property and pyrolysis behavior between different reconstituted tobacco products caused by fibers and textural structures were researched. The results showed that: 1) The average length, width and length distribution of fibers in different samples differed greatly, the average length of fibers in the samples ranged from 0.95 to 1.44 mm, the average width from 21.0 to 49.6 μm. 2)Two microstructurally different fibers were observed, the one was soft and crimped with flat and hollow microstructure and possessed better interweaving property, the other was stiff with round and solid microstructure. 3) There were obvious differences in the vessel wall thickness of undissociated tobacco stem and the microporosity of stratifications between difference samples. High proportion of long fiber increased tensile strength, wider fiber increased bulk thickness. The samples with open microstructure presented lower tensile strength and higher air permeability; and the samples with open and porous microstructure and low fiber lignification degree had lower pyrolysis temperature and higher weight loss rate. The fiber composition and microporosity affect the pyrolysis behavior of reconstituted tobacco significantly.