Investigation of millimeter wave stealth technology was implemented to improve ground target’s survivability in future battlefield under the threat of detection and guidance by passive millimeter wave. After considering the disadvantage of passive stealth, a new active stealth method was put forward based on the radiation characteristics of the target and background. Then, the theory of stealth method was analyzed, and the jamming power area density of different background under a typical bandwidth was obtained after the modeling calculation was processed. Finally, The stealth characteristics of the target were tested by outfield experiments. The experimental data shows that the radiant difference between the target and background is obviously depressed after jamming, and the technical feasibility of the stealth is also verified.