The technology of smart skin radar stealth is belong to active radar stealth, and active radar stealth is an important branch of target radar signature control technology, which is also known as radar stealth technology. A smart skin radar stealth device is mentioned in an United States patent, but there was not detailed description about the device. This paper wants to make a quantitative analysis of the smart skin radar stealth device. 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 phase shift, incident frequency, incident angle, spatial relationship and other factors is derived; finally, the stealth performance influenced by incident frequency, incident angle and spatial position is discussed by numerical simulation.