Abstract: Poly(p-phenylene vinylene) (PPV) is one of the earliest discovered photoluminescent polymer with regular structure and high fluorescence quantum yield. Many methods have been reported for the synthesis of PPV, but most of them are not feasible for controlling the molecular weight and molecular weight distribution of PPV. Confining chemical reactions in porous channels is a common method to control the chemo- and stereo- selectivity and modulate the reaction rate. Therefore, many methods have been developed for loading the catalysts inside porous materials to regulate chemical reactions and polymerizations. To this end, palladium catalysts were selectively loaded into the pores of mesoporous silica materials with different pore sizes for the controlled synthesis of PPV. Six types of mesoporous palladium nanoreactors were prepared using three different types of mesoporous silica materials (dendritic mesoporous silica nanospheres, SBA-15, and low aspect ratio SBA-15). Their stable mesoporous structure and efficient loading of palladium catalysts in the pores were determined by nitrogen adsorption-desorption analysis and transmission electron microscopy. The palladium content was measured by plasma emission spectroscopy. Heck coupling polymerizations between dihexoxy substituted diiodobenzene and divinylbenzene monomers were thus ushered inside the nanopores to get the molecular weight of the PPV product controlled through the spatial confinement effect of the pores. The reactions were carried out at 135 °C for 3 d and the polymeric products were directly subjected for structural analysis. Fourier transform infrared spectroscopy showed that the obtained PPV consisted of para-substituted benzene rings and trans-ethylene groups, similar to the literature reported ones. The molecular weight of PPV was measured by gel permeation chromatography. It can be found that PPV with narrower molecular weight distributions was obtained in six kinds of palladium-loaded nanoreactors in comparison with that obtained in homogeneous catalytic system. The dispersity of the PPV obtained through this strategy reached as low as 1.53.