A novel kind of incompletely condensed polyhedral oligomeric silsesquioxane (TAP-POSS) containing allyl groups was successfully synthesized, and its structure was characterized by fourier transform infrared, nuclear magnetic resonance ((1)H-NMR and (29)Si-NMR) and X-ray diffraction. In addition, TAP-POSS was hybridized with 2,2'-diallylbisphenol A (DBA)-modified 4,4'-bismaleimidodiphenylmethane (BDM) resin to develop a new kind of hybrids with simultaneously improved thermal stability and dielectric properties. Compared with BDM/DBA resin, the BDM/DBA/TAP-POSS hybrids have obviously increased thermal resistance reflected by the increased glass transition temperature (T (g)) and char yield at high temperature. For example, the T (g) of modified BDM/DBA resin with only 3.0 wt% TAP-POSS is 330 A degrees C, which is 36 A degrees C higher than that of pure BDM/DBA resin. On the other hand, the dielectric properties over wide frequency and temperature ranges are thoroughly investigated, and results show that the dielectric constant and loss of all hybrids are not only lower than those of BDM/DBA resin over the whole frequency and temperature ranges tested, but also exhibit smaller dependence on temperature and frequency. These phenomena can be explained from the variety of cross-linked structure induced by the presence of TAP-POSS. The outstanding integrated properties of BDM/DBA/TAP-POSS hybrids suggest that TAP-POSS has advantages over conventional POSS, thus the method proposed herein is a new approach to develop high performance structural/functional materials for cutting-edge industries.