Copolymerization of octamethylcyclotetrasiloxane (D4) with 1,3,5,7-tetrametyl-1,3,5,7-tetravinylcyclotetrasiloxane (V4) by heterogeneous acid catalysis has been carried out. In order to find the optimal conditions of the reaction, a second-order experimental design was performed with reaction time, reaction temperature, amount of catalyst, and the initial molar fraction of the monomers as independent parameters. By data processing, response surfaces of monomer conversion and copolymer composition were obtained, which were studied by eigenvalues analysis and by plotting in 2-D fields. It was found that the most important factors of influence were reaction temperature for the monomer conversion and the initial monomer molar fraction for the copolymer final composition.