Abstract: According to the problem of the stress on the coal mass highly affected to the permeability of coal mass during the seam water injection and vadose proc ess, with a self researched and developed penetration rate measuring system of coal and rock samples, a test measuring and test analysis was conducted on the functi on law between the effective surrounding pressure and the coal sample penetration rate A ftting equation of the mutual influences between the coal sample penetration rate and the effective surrounding pressure was obtained and the coal sample penetration rate to the sensitive coefficient of effective surrounding pressure also was obt ained.The results showed that with the effective surrounding pressure increased, the penetration rate of different coal samples would be decreased in order and the one -place secondary polynomial variation law could be met.The penetration rate of different coal samples would be similar to the sensitivity of effective surrounding pressur e variation.