Abstract:The original permeability of limestone is very weak,and its excellent permeability results from the cracks rebuilt by groundwater. With the excavation of a limestone tunnel and drainage of groundwater,the velocity of permeability,which is very slow under undisturbed natural hydro-geological conditions,will be improved dramatically. The component solved under low-order resolving reaction condition is drained quickly and fresh groundwater with low concentration is supplied continuously. The evolution of limestone permeability will be accelerated in the disturbed hydro-geological environment,and the low-order chemical reaction will be the prevailed one which will cause significant evolution of permeability in drainage tunnel in the sense of engineering. A parallel board model and PWP equation are adopted to establish the chemical dynamic evolutiom model of limestone permeability in drainage tunnel. The crack is simulated with the parallel board,the dissolution damage of the crack wall is simulated by parallel board model calculated by PWP equation,and the evolution of the surrounding limestone permeability is simulated by introducing the conception of seepage tensor for early drainage period. The presented method can also be used in the evaluation of reservoir leakage,the influence of tunnel drainage on geological environment,stability of rock mass and life of a limestone engineering etc. Finally,an example is introduced .