In order to study combustion performance of deterrent coated granular propellant and slotted stick propellant with constant volume, 7/19 propellants and 9/19 stick propellants were prepared by coating polymeric flame TiO₂. The closed-bomb tests of slotted stick propellant and deterrent coated propellant were carried out, and combustion performance of deterrent coated propellant and mixed charge with constant volume was investigated. The influence of mixed ratio of slotted stick propellant and deterrent coated propellant in different loading densities on combustion was studied. Combustion mechanism of slotted stick propellant and deterrent coated propellant was analyzed. The results show that loading density impacted the combustion of mixed charge, the higher loading density can increase burning progressivity and decrease erosive combustion. In this experiment, the suitable mixed ratio of slotted stick propellant and deterrent coated granular propellant is 4:6 and 3:7 when loading density is 0.20 g·cm^-3 and 0.32 g·cm^-3, which can lead to a good combustion progressivity. It was also found that slotted stick propellants and deterrent coated propellants interact seriously in the early stages of combustion.However, as the combustion progresses, the interaction between them gradually weakens.