Using Al powder, Al-12Si and Al-20Si alloy powder as phase change medium and fly ash as matrix material，metal/ceramic based high-temperature shaped composite phase change materials were prepared by mixed sintering method under air and vacuum sintering atmosphere. The effects of the Al-Si relative content and sintering atmosphere on the heat storage performances of materials were investigated. The results show that the oxidation of Al is inevitable when the three kinds of metal powders are used to prepare composite phase change materials, the relative content of Si exceeds the eutectic point composition. The state point during solidification is always in the two-phase zone of eutectic phase and Si phase, and the unoxidized Al transforms into Al-Si eutectic phase. Sintering in air is beneficial for Al to form a dense oxide film and prevent its further reaction. The density and latent heat of phase change of materials sintered in air are higher than those sintered in vacuum. Among the three kinds of composite phase change materials, Al powder composite phase change material has the worst thermal stability, while Al-12Si composite phase change material has the highest latent heat of phase change and retention rate, and outstanding thermal stability and heat storage performance.