Abstract: When chemical reaction takes place between the active aggregate and the alkalinity in cement,the active aggregate will expand with water,and destroy the concrete.In this paper,97 groups of experiments were made on the alkalinity activity degree in 12 limestone material fields with 3 methods,such as lithofacies method,mortar club method,rock pole method,along the Middle of Southto-North Water Diversion in the Taihang Mountain in northern Henan.The major results indicate that most of the ∈2zh and O2s limestone has no alkalinity activity components,which is judged to have un-alkalinity activity,and with no harm to the project;most of the O2x limestone has alkalinity-silicic acid activity components,the expansion ratio of some samples is greater than 0.1% with the mortar club method,which is judged to have alkalinity-silicic acid activity.