A type of cavitation pattern named triangle cloud cavitation structure, which was formed by tip clearance cavitation, shear layer cavitation and tip leakage vortex cavitation, would cause some adverse effects on its shedding cavity at the trailing edge, such as diminished overall performance and efficiency, rotating instabilities, noise and vibration. Thus the mechanism of the phenomenon should be understood. For the sake of deeply studying the process of cloud cavitation shedding in the tip region of an axial-flow model pump, the filter-based model with modified density of RNG k-ε turbulence model was embedded into the commercial software ANSYS CFX by the secondary development technology for simulation. Simultaneously, the homogenous cavitation model was also adopted to simulate the unsteady cavitating turbulent flows. Some significant results were summarized. The simulation results were compared with experimental values. It could be concluded that the simulation results were agreed well with experimental values by successfully predicting the periodic process of cloud cavitation shedding in the tip region with DCMFBM turbulence model. With the rotation of blade, the shedding cavity was migrated towards the pressure side of neighboring blade and affected the load distribution of the pressure side;meanwhile, it also had impact on its load distribution on the suction side. A radial jet from the hub to the rim was found near the exit of blade, when it reached the blade tip, it eventually impinged on the cavity surface near the wall, which caused the formation of an open cavity with shed bubbly clouds. Then it was entrained into the TLV, forming an unstable and noisy spiraling pattern, which would enhance the instabilities of the flow field in tip region. It was possible that hub vortices characterizing wing-body junctions might have also played a role.