Abstract: Active radar stealth technology is an important branch of target radar signature control technology (which is also called as stealth technology). A quantitative analysis is made for an active radar stealth device mentioned in a United States patent, and the stealth device is one kind of smart skin. Firstly, the basic working principle of the device is described, and then the constraint equations of electromagnetic field is given. Secondly, the quantitative relationship between the transfer phase, incident wavelength, incident angle, spatial relationship and other factors is derived. Finally, the stealth performance influenced by incident wavelength, incident angle and spatial position is discussed by numerical simulation, and some meaningful conclusions are drawn.