© 2021, King Fahd University of Petroleum & Minerals.The use of natural fibres in the production of polymer composites has become widespread, but these materials are easily flammable. In this study, the fire resistance of flax fibre composites produced with polyurethane (PU)-based shape memory polymer matrix is improved with diammonium phosphate, polydopamine and titanium dioxide. Flax fibres were treated with diammonium phosphate and then coated with polydopamine, shape memory polymer matrix reinforced with titanium dioxide. Scanning electron microscope images of the produced composites before and after combustion were examined, and the protective char layer of polydopamine was observed. Thanks to this layer, the composite structure preserved its integrity after combustion and the mass loss decreased from 82 to 69%. Limiting Oxygen Index value of non-coated flax fibre composite was measured as 20%, while that of PDA-coated TiO2-doped flax fibre composite was recorded as 24% showing significant improvement for the PDA-coated TiO2-doped flax fibre composite. Flame propagation rate decreased from 81 to 21 mm/min in the horizontal burning test. The effect of polydopamine and titanium dioxide on fibres and PU-based shape memory polymer matrix was investigated by thermogravimetric analysis/differential thermal analysis. This study clearly proved that the fire resistance of natural fibre composites produced from PU-based shape memory polymer matrix is improved with diammonium phosphate, polydopamine and titanium dioxide.