First,2,7-dibromospiro[fluorene-9,9′-（2′,7′-dihydroxy-xanthene）]（Compound Ⅲ） was prepared through such three steps as Br₂/Fe bromination,CrO₃/Ac₂O oxidation and resoreinol/ZnCl₂ catalytic condensation,with fluorene as the starting material.Then,2,7-dibromospiro[fluorene-9,9′-（2′,7′-dihydroxy-1′,8′-disulfonic-xanthene）]（Compound Ⅳ） was synthesized via the sulfonation of Compound Ⅲ with concentrated sulfuric acid and was characterized by means of IR,1H NMR and UV-Vis,etc.Finally,the effects of reaction temperature,reactant molar ratio and reaction time on the sulfonation yield were investigated,and the optimal reaction conditions for Compound Ⅳwith a yield up to 86.5% were determined,that is,adding 1g of Compound Ⅲ together with 3mL concentrated sulfuric acid for the sulfonation at 70℃ for 2h.