Ferroaluminate cement has an effective resistance to seawater erosion due to its advantages in the application of marine engineering. The effect of mixing with seawater and metakaolin on the fluidity, setting time, heat of hydration, electrical resistivity, internal temperature, chemical shrinkage, compressive strength, and hydration products of ferroaluminate cement paste was investigated. The results indicate that the addition of metakaolin reduces the fluidity and shortens the setting time of the cement paste. The chemical shrinkage at 72 h, electrical resistivity and internal temperature peak at 24 h all decrease. However, the heat release rate, chemical shrinkage, electrical resistivity and the formation of ettringite at early age can be accelerated when the content of metakaolin is less than 20%. When the cement is mixed with seawater, the hydration of cement can be accelerated and the fluidity and setting time can be decreased. The formation of the Friedel’s salt can occur. The mixing of seawater and appropriate amounts of metakaolin in ferroaluminate cement promotes more ettringite, thus increasing the compressive strength of ferroaluminate cement paste. The compressive strength of different specimens mixed seawater at 180 d is improved by 48.6%-80.2%, compared to that of the sample mixed with fresh water.