In this paper, the gypsum-based self-leveling mortar is prepared using FGD gypsum-based α-hemihydrate and molybdenum tailings as the binder and aggregate respectively. The effects of different aggregate on fluidity, early and absolute strength are studied. The results indicate molybdenum tailings can replace quartz sand as aggregate to produce self-leveling mortar, and the performance indexes meet the standard requirements of China.The main differences between molybdenum tailings and quartz are the fineness and morphology of particles. Moreover, using molybdenum tailings as aggregate, the early strength is slightly better than that of the ordinary gypsum-based self-leveling mortar.