Flue gas desulphurization gypsum（FGD） metakaolin（MK） cement system were prepared and investigated. Results show that compared with the pure cement paste， initial and final setting time of the compound system are much longer， the period between initial and final setting time is much shorter. Fluidity of the compound system is at the same level of pure cement paste. Compressive strength of the samples increases with increasing curing age， and compressive strength of the sample with SO3 to Al2O3 molar ratio of 1.0∶1.0 is the highest. The samples show a little expansion but not beyond 0.39%. The compressive strength development law of the samples cured for 28d is consistent with expansion ratio. It means that more formation content and higher formation rate of AFt contribute to higher expansion and ideal compressive strength. The hydration products include AFt and C A H at the same time. A few AFt transforms into AFm replacing Al3+ by Si4+ in later hydration period.