In order to investigate the feasibility and superior of volcanic rocks used as pozzolan in cement-based composite,the volcanic rocks from the east region of Jiangxi Province, China, were collected for this research.They include tuff, lava, perlite, and laval tuff.The analysis result of chemical composition displayed that the volcanic rocks contained high quantity of SiO2+Al2O3 (>77%), especially great amount of SiO2 (>64%), which are far more than the requirements of composition in the relevant standards.XRD results shown that the volcanic rocks were mainly composed of glassy groundmass, quartz, sanidine, and sodium feldspar.The amorphous phase content of volcanic rock could be obtained from XRD data.The volcanic rocks were comprised of amorphous phase no less than 62%.Pozzolanic activity component for pozzolan was calculated by the product of chemical composition (SiO2 + Al2O3) content (%) and amorphous phase content (%).It declares proportion of pozzolanic activity composition to be able to react during the second hydration reaction without the consideration of particle size, and is appraised as the characteristic index of potential pozzolanic activity to indicate internal capacity of pozzolan to react with CH, instead of chemical composition alone.These volcanic rocks possessed pozzolanic activity components no less than half of whole rock composition.