Polymer foam materials play a key role in many applications. Fabricating foamed materials from polymer blends are fascinating and challenging in application and scientific research field, because foamed polymer blends afford the potential of combining the advantageous properties of each component within the foamed material, and take advantage of the multiphase characteristics for the foaming process. Apart from the basic foaming conditions (temperature, pressure et al.), the composition and structure of polymer blends will affect the material properties (such as crystallinity, interfacial tension, melt strength, solubility and diffusivity of foaming agent) and ultimately determine the foam morphology and properties. So far there have been many reports about the compatibilization of immiscible polymer blends, but few of them are focused on the effect of compatibilizers on foaming behaviour of polymer blends. In this presentation, we report the recent results about the influence of compatibilization on foaming behavior of polymer blends (such as polyethylene/polystyrene alloy). It has been found that the compatibilization of graft copolymers or nanoparticles shows interplay with the composition of blends in determining the foaming behavior under studied experimental conditions. This phenomenon may be related to the formation of different morphology at various compositions of polymer blends. Some insight has been presented.