Abstract: Thermoelectric cement-based composite materials can convert thermal energy in building environments into electrical energy, and as a new energy conversion approach, have received widespread attention and research in recent years. There is a problem of mismatch between the optimal working temperature and environmental temperature in the application of thermoelectric cement-based composite materials, and the low thermoelectric conversion efficiency restricts the application of thermoelectric cement. This study incorporated expanded graphite (EG)/paraffin wax (PW) phase change composite materials prepared by melt blending into cement-based materials to prepare phase change expanded graphite/cement composite materials. The effect of the addition amount of phase change composites on the thermoelectric properties of cement-based materials was studied. The increase in the content of phase change composites regulates the temperature range for the optimal thermoelectric performance of cement-based composite materials. The test results show that the temperature point corresponding to the maximum thermoelectric performance is adjusted from 55℃ to 60℃ and 65℃. The corresponding Seebeck coefficient is −24.65, −30.97 and −30.90 μV/K. The power factor is 1.39, 1.57 and 1.67 μW·m⁻¹·K⁻². Thermoelectric merit (ZT) value is 5.53×10⁻⁵, 6.50×10⁻⁵ and 7.07×10⁻⁵. Phase change composites absorb heat during the phase change process, reducing the heating rate of cement-based materials, weakening the decrease in Seebeck coefficient caused by an increase in carrier concentration due to temperature rise, adjusting the temperature range corresponding to the peak power factor of cement-based materials, and regulating the temperature range of use of thermoelectric cement-based composite materials. This study provides a new approach and method for improving the performance of thermoelectric cement-based composite materials.