The impact of the bleed off-take cavity within aspirated blades on the aerodynamic performance of a highly loaded compressor cascade was explored. Three-dimensional Navier-Stokes simulations were conducted in rectangular compressor cascades after validation against experimental results were done. Five different off-take configurations with varying suction location were numerically evaluated. The results show that the regularities of the suction flow distribution on the suction slot inlet greatly influence the benefits of boundary layer suction. The distribution style greatly depends not only on the flow condition of the blade passage, but also on the realization of the suction process and the geometry of the cavity inside the aspirated blade. The low kinetic fluid in the endwall region compared with that around the midspan is usually prone to be sucked into the suction slot. The distribution of the suction mass flow along the spanwise direction would be symmetrical if the suction position is properly selected and the inside off-take cavity is well designed, even though the bleeding system has been simplified to be asymmetrical as employed in the present document.