To reduce the erosion of R2 high-energy propellant， a new composite erosion inhibitor based on silicon/modified nano TiO₂/paraffin was designed and prepared. The erosion-reducing performance of the new type of composite erosion inhibitor was studied by a semi-closed bomb test with the standard erosion inhibitor as the reference material. The erosion inhibition mechanism of the new composite erosion inhibitor was studied by scanning electron microscope-energy dispersive spectrum （SEM-EDS）， and its effect on the static combustion property of propellant was investigated using a closed bomb test. The results show that the new composite erosion inhibitor has a significant effect on reducing erosion. The erosion inhibition rate can reach 34.24% when the addition of erosion inhibitor is 5%. Decamethylcyclopentasiloxane （D5） in the erosion inhibitor is decomposed at high temperature， and the silicon oxide nanoparticles produced by the decomposition can effectively block the carburization reaction by adhering to the inner wall of the erosion tube. Since R2 propellant added with the new composite erosion inhibitor has higher combustion progressivity， the energy is released at the later stage of combustion which is beneficial to reduce the erosion.