Physical modification and chemical modification were used to modify fluorgypsum. Effect of physical modification and chemical modification on the performance of fluorgypsum was studied, and the mechanism of modification was discussed by testing the phase composition and microstructure of modified fluorgypsum, using XRD and SEM. The results showed that fluorgypsum activity was excited effectively by physical modification and chemical modification. Physical modification decreased CaSO4 grain size and structure regularity, and increased fluorgypsum specific surface area, and the optimum specific surface area was 4600-4900cm2/g. Chemical modification accelerated fluorgypsum hydration and CaSO4•2H2O growth, and increased CaSO4•2H2O grain size and slenderness ratio. The strength of fluorgypsum was exerted effectively by chemical modification.