Metatitanic acid/urea-formaldehyde microcapsules were synthesized to inhibit the erosion of gun barrel resulting from the propellant combustion. The microcapsules were prepared by one-step in-situ polymerization method. SEM and EDS were employed to characterize the morphology, core-shell structure and the chemical composition of the microcapsules. FTIR spectra and XRD patterns confirmed the formation of crystalline urea-formaldehyde resin on the surface of the metatitanic acid particle. TG results showed that the thermal decomposition residue weight ratio of the microcapsules in air was 12.8 %. Kinetic parameters of thermal decomposition of propellant with and without the microcapsules were calculated based on the DSC results, respectively, which proved the good compatibility between the microcapsules and the double-base propellant. Erosion tube comparative test showed the wear-reducing efficiency reached 18.54 % with 1.5 wt.% addition of microcapsules. The combination of metatitanic acid and urea-formaldehyde resin surprisingly resulted in a synergistic effect, which was attributed to the better dispersibility of TiO(2)particles generated by metatitanic acid microcapsules. The metatitanic acid/urea-formaldehyde microcapsules exhibit a potential application for propellant erosion additive.