Abstract: In a two-phase flow, the vortex merging influences both the flow evolution and he particle motion. With the blobs-splitting-and-merging scheme, the vortex merging is alculated by a corrected core spreading vortex method (CCSVM). The particle motion n the vortex merging process is calculated according to the particle kinetic model. The esults indicate that the particle traces are spiral lines with the same rotation direction is the spinning vortex. The center of the particle group is in agreement with that of the merged vortex. The merging time is determined by the circulation and the initial ratio of the vortex radius and the vortex center distance. Under a certain initial condition, a stretched particle trail is generated, which is determined by the viscosity, the relative position between the particles and the vortex, and the asymmetrical circulation of the two merging vortices.