The factors which lead to errors in the experiment of studying the change law of permeability of coal-rock were analyzed.According to the theoretical analysis on the procedure of experiment and data processing,it was considered that irrational operation in experiment and irrational choose of parameters in data processing are two important reasons for the errors in determining the permeability of coal-rock.These two factors leading to errors were analyzed,and some corresponding improvements and suggestions to decease the affection of the two factors were proposed.It has important significance for the permeability research experiment.