Influence of the curing regimes that involved different temperatures on mechanical properties of magnesium oxychloride (MOC) cement-based composites was investigated. It shows that introduction of the high temperature curing at 75 °C can lead to significant improvements on compressive strengths of these MOC cement-based composites that had ambient curing at the early age. However, introduction of the high temperature curing has clear detrimental effect on water resistance performance of the composites. The high temperature curing induced micro-characteristic changes in the MOC cement-based composites account for the clear macro-mechanical variations.