The hydration for the system of fluorogypsum and 20wt% blast furnace slag was investigated at liquid/soild ratio of 0.45 for 1, 3, and 7 days by using 3 kinds of accelerators such as K2SO4 Al2(SO4)3 $.$16-18H2O and AlK(SO4)2$.$12H2O After curing the hardened specimen was characterized by the compressive strength the content of combined water XRD, DTA and SEM It was found that the activating effect was increased in the order of K2SO4 <Al2(SO4)3 <AlK(SO4)2 The combined water was determined to be 85% and the com-pressive strength of 200kg/cm2 was obtained after 3 days of curing for the AlK(SO4)2 accelerator. And also it was found that the ettringite was observed only in the AlK(SO4)2 system.