In order to design the optimum mix ratio of metakaolin-based geopolymer, the effects of raw material composition on the compressive strength of the geopolymer was studied. In this paper, the effects of the molar ratios of SiO2/Al2O3, Na2O/Al2O3 and H2O/Al2O3 on the 7-day compressive strength of metakaolin-based geopolymer were analyzed. The empirical mole ratio was then summarized. The results show that when the molar ratio of SiO2/Al2O3 is around 4 and the molar ratio of Na2O/Al2O3 is 0.9~1.1, the 7-day compressive strength of metakaolin-based geopolymer is maximum (over 65MPa).The effect of molar ratio of H2O/Al2O3 on the 7-day compressive strength of the geopolymer is limited. The effect of the molar ratios of SiO2/Al2O3, Na2O/Al2O3 and H2O/Al2O3 on the 7-day compressive strength of the metakaolin-based geopolymer decrease successively.