Novel siloxane-containing benzoxazines were prepared from phenol, paraformaldehyde, and bis(p-aminophenoxy)siloxane. The curing reaction of obtained benzoxazines was studied by in-situ Fourier Transform infrared spectroscopy. The curing kinetics and kinetic model were investigated by nonisothermal Differential Scanning Calorimeter. The kinetic data indicated that the activation energy shifted to a higher value with the increase in benzene ring content in benzoxazines, and the siloxane-containing benzoxazines followed an autocatalytic curing model based on Friedman method. Because of the introduction of aminophenoxysiloxane instead of aminopropylsiloxane, the siloxane-containing polybenzoxazines have a higher thermal stability as confirmed by thermogravimetric and pyrolysis analyses, especially for the bis(p-aminophenoxy)diphenylsiloxane-based polybenzoxazine with an initial decomposition temperature of 420 degrees C and a char yield of 74%.