Abstract: We studied the influence and mechanism of external factors including activator and curing temperature on the mechanical properties of geopoylmer. NaOH and Na₂SiO₃ were used as the activator. And the sensitivity of the mechanical properties of metakaolin-based geopolymer to the activator modulus, the activator concentration, the curing temperature, and the curing time was analyzed by orthogonal tests. The mechanism of the activator concentration influencing geopolymerization and synthetics properties was investigated by the microcalorimetric, infrared spectrum and scanning electron microscope-energy disperse spectroscopy. The test results show that the concentration of activator is the most important factor for mechanical properties of geopolymer. The compressive strength of geopolymer increases with the increase of the activator concentration. The activator modulus ranks second, the increase in which results in the decrease of the geopolymer strength. Higher degree of polymerization is obtained when the concentration of activator increases. The polymerization reaction tends to full completion and mechanical properties of geopolymer increase subsequently, the strength of geopolymer increases to 99.98 MPa when the activator concentration reaches 80%, moreover the ratio of silicon to aluminium is greater than 1.