In this study, we Investigated the miscibility behavior and mechanism of interaction of poly(methyl mechacrylate) (PMMA), poly(vinyl pyrrolidone) PVP, and PMMA-co-PVP blends with octa(phenol)octasilsequioxane (OP-POSS). For the PMMA/OP-POSS binary blend, the value of the association constant (K-A = 29) was smaller than that in the poly(vinyl phenol) (PVPh)/PMMA (K-A = 37.4) and ethyl phenol (EPh)/PMMA (K-A = 101) blend systems, implying that the phenol groups of the OP-POSS units in the PMMA/OP-POSS blends interacted to a lesser degree with the C=O groups of PMMA than they did in the other two systems. In addition, the ionic conductivity of a LiClO4/PMMA-co-PVP polymer electrolyte was increased after blending with OP-POSS.