Abstract: Flame-retardant poly(butylene succinate) (PBS) composites were prepared by melt blending using intumescent flame retardant (IFR) and modified basic magnesium sulfate whisker (MHSH), and their mechanical performance, flame-retardant properties and smoke suppression were investigated. The results indicated that the incorporation of MHSH could enhance the mechanical performance and flame retardancy of the composites. When the contents of IFR and MHSH were set as 23 wt % and 2 wt %, respectively, the composites achieved a LOI value of 39.8 vol % and UL 94 V-0 classification. Their tensile strength, bending strength and impact strength also increased by 33.33 %, 6.65 % and 21.80 %, respectively, compared with those of the composites only containing 25 wt % of IFR. The addition of MHSH could effectively reduce the total smoke release amount and the release rate of carbon monoxide and carbon dioxide for the composites due to its synergistic effect, thus reducing the fire risk of the composites.