The dissolution rates of alkali activated metakaolin/GGBFS in hydrochloric acid with various pH values were investigated, and X ray fluorescence(XRF）, X ray diffraction(XRD) and Fourier transform infrared(FTIR) were used to analyze the metakaolin and the hydrochloric acid insoluble of metakaolin based geopolymer. It is found that the hydrochloric acid insoluble of metakaolin based geopolymer is metakaolin which is unreacted when the pH value of hydrochloric acid is from 0 to 2 Thus the geopolymerization reaction level of metakaolin can be determined based on the content of hydrochloric acid insoluble. Under the present alkali activation environment the hydration reaction of GGBFS is nearly completed. The acid dissolution tests of alkali activated metakaolin/GGBFS show that the addition of GGBFS increases the geopolymerization level of metakaolin in most cases. With a certain GGBFS content, the reaction level of metakaolin decreases with the increase in activator modulus, and increases with the increase in liquid solid ratio of system, of which promotion impact is more significant with a fewer GGBFS content. The reaction level of metakaolin increases with the increase in GGBFS content when the activator mass fraction is low, on the other hand, when the activator mass fraction is relative high. The GGBFS content corresponding to the highest reaction level of metakaolin is gradually reduced with increase in activator mass fraction.