Based on the stress sensitivity experiments of various rank coals, the influence of the effective stress on the permeability of different rank coals is studied. It is shown that in the same range of the effective stress variation, the decrease of the low-rank coal permeability is larger than that of the medium-rank and high-rank coals; The permeability variations of the low-rank and high-rank coals more consistently follow an exponential law than the medium-rank coal; In the low effective stress range, the damage coefficient of the permeability and the stress sensitive coefficient of the low-rank coal are greater than those of the medium-rank and high-rank coals; Under the identical effective stress, the cleat compressibility of the low-rank coal is greater than that of the medium-rank and high-rank coals; The cleat compressibility decreases with the increase of the effective stress, and it is not constant. Fitting results of evaluation parameters of the stress sensitivity show that the damage coefficient of the permeability and the cleat comperssibility of the low-rank and medium-rank coals follow an exponential law, but for the high-rank coal, they follow a linear function; the stress sensitive coefficient of various rank coals follows an exponential law.

various rank coals  /  effective stress  /  injury coefficient of permeability  /  stress sensitive coefficient  /  cleat comperssibiilty