Abstract: Air intake with fences installed at the entrance is investigated at low speed. With fences at a high angle of attack the steady and dynamic distortions are effectively reduced and the total pressure recovery is increased at the exit.These improvements are shown to be closely related to the reduced extent of separation along leeward wall of the intake by the fences at the angle of attack. A flow model is suggested to describe the flow in the channels formed by the fences. With this model in mind, the mechanism of the fences can be easily imagined and the performance of the slanted inlet with fences can be predicted. The effects of the position, lengths and the number of the fences on the performance of the inlet are investigated. The difference between a slanted and a pilot inlet both with fences are compared and an intake with an S-duct and fences are evaluated. Combined with less radar reflection the multi-channel inlet is shown to be attractive. The above related investigation will be helpful in intake fence design.