Abstract: The concept of rescaled-range (R/S) analysis of fractal theory is inrtoduced in this paper.It is discussed,that the theoretical significance and the practical computing method of the Hurst exponent H,and use H for the prediction of gas emission in coal mine.Base on the fractal calculation of gas emission in coal mine and according to the value of structure fractal dimension,a fractal prediction for the incremental tendency of gas emission in coal mine is conducted.