Flow-induced vibration (FIV) refers to the vibration phenomenon caused by the interaction between a fluid and a solid structure, primarily induced by unsteady aerodynamic or hydrodynamic forces generated as the fluid flows around the structure. This study investigates the flow-induced vibration characteristics of a truncated cylinder at a low Reynolds number. Truncating the forebody of the cylinder at intervals of 15°, the cylinder is divided into bluff bodies with different cross-sections. Numerical simulations are conducted at a Reynolds number of 100 and a reduced velocity range of Ur = 2–20. The results show that the flow-induced vibration characteristics of the truncated cylinder are divided into three stages depending on the cross-sectional angle: typical VIV at α = 0°–60°; extended VIV at α = 75°–120°; pure galloping at α = 135°–180°. There are 10 distinct vortex-shedding modes behind the cylinder. The findings highlight the significant influence of the truncated cylinder's leading edge (forebody) on flow separation and vortex shedding.