Abstract: A finite element model (FEM) is established with proper constitutive laws of materials, element types, meshing technology, and boundary conditions. After being verified with experimental results, the FEM is used to study the shear strength of circular concrete-filled steel tubular (CFST) members with a circumferential gap between the tube and concrete. The numerical investigation indicates that the existence of the gap decreases the ultimate shear strength of CFST members, and the influence is closely related to the gap ratio and the span-to-depth ratio. However, the influence of the concrete strength, steel strength and steel ratio on the shear strength reduction is less significant. When the span-to-depth ratio equals to 0.5, the gap has the most significant influence on the mechanical performance of CFST members with initial concrete imperfection. Based on the parametric study, a simplified formula is proposed to calculate the shear strength of circular CFST members with a circumferential gap.