To improve the reaction performance and reduce variations in the output pressure of Al/KClO₄ pyrotechnic compositions， in-situ replacement method was applied to replace the inert layer of micron-sized aluminum with TiO₂ layer. Scanning electron microscopy （SEM）， X-ray diffraction （XRD）， differential scanning calorimetry-thermogravimetry （TG-DSC） and thermal analysis were conducted to study the microstructure， composition， thermal and combustion properties of Al@TiO₂ particles. The consistency of output pressure was analyzed through ignition experiments. The results show that aluminum coated with TiO₂ layer is well prepared by in-situ replacement method. The explosives made with Al@TiO₂ have an 18% lower in activation energy （E_a） and a slightly lower enthalpy compared to ordinary Al. The standard deviation of output pressure decreased from 0.28 MPa to 0.13 MPa. The thermal behavior of aluminum and potassium perchlorate was enhanced by the TiO₂ layer， significantly improving the consistency of output pressure.