The aerodynamic performance of a kind of air inlet system with perforated plate used in auxiliary power units (APU) was investigated experimentally. The experimental results show that with the increase of mass flow rate

the outlet total pressure recovery coefficient and total pressure distortion coefficient decrease. The total pressure recovery coefficient decreases slightly in the fixed total mass flow rate case

but decreases linearly in the fixed proportion case. The total pressure distortion is mainly influenced by the imperforate area of the whole perforated plate in the circumferential direction and the flow passage curvature in the radial direction. With the increase of orifice ratio

the outlet total pressure recovery coefficient increases accordingly. The total pressure distortion of power section is mainly influenced radially in different orifice ratios; the distortion of load section is mainly influenced circumferentially in small orifice ratio and radially in large orifice ratio.