Dynamic variation rule of coal reservoir permeability is one of the most important issues in development geology field of coalbed methane（CBM）. According to the method of dimensionless production analysis，the whole drainage and production process is divided into four stages as water drainage，unstable gas production，stable gas production and gas production decline based on drainage and production data of fifteen high-rank CBM wells in southern Qinshui Basin. The coal permeability variation value at different stages were analyzed with production data by material balance method. The dynamic variation value and mechanism of permeability in high-rank CBM wells at different drainage and production stages are interpreted in five aspects：permeability variation trend，leading mechanism，systemic energy，phase composition and dynamic productivity. The study reveals that the coal bed permeability in high-rank CBM wells show the trend of decline-recovering-rising during produced process. Effective stress effect and matrix shrinkage effect directly control the dynamic variation characteristics of the coal reservoir permeability. Characteristics of adsorption（desorption）control the acting time and strength of the matrix shrinkage effect fundamentally.