In the paper, a type of phase change metamaterial for tunable infrared stealth and camouflage is proposed and numerically studied. The metamaterial combines high temperature resistant metal Mo with phase-changing material GST and can be switched between the infrared "stealthy" and "non-stealthy" states through the phase change process of the GST. At the amorphous state of GST, there is a high absorption peak at the atmospheric absorption spectral range, which can achieve infrared stealth in the atmospheric window together with good radiative heat dissipation in the non-atmospheric window. While at the crystalline state of GST, the absorption peak becomes broader and exhibits high absorption in the long-wave infrared atmospheric window, leading to a "non-stealthy" state. The relationship between the infrared stealth performance of the structure with the polarization and incident angle of the incident light is also studied in detail. The proposed infrared stealth metamaterial employs a simple multilayer structure and could be fabricated in large scale. Our work will promote the research of dynamically tunable, large scale phase change metamaterials for infrared stealth as well as energy and other applications.