In the previous result, the flexural strength of geopolymer prepared was affected by the evaporation of water content or the shrinkage rate in the curing process of specimen. We investigated the effect of SiO2/H2O ratio on the physical property of geopolymer prepared in this research. The specimen of geopolymer tile was made from mine tailing and melting slag. The maximum flexural strength was obtained at SiO2/H2O ratio of 0.21 under our experimental condition. And the lowest was obtained at SiO2/H2O 0.41. EDS analysis was acted to elucidate this cause. According to the results, it was due to the extent of geopolymerization at the inside and outside of specimen.