In order to further research the size of released circle and variation regularity of soft rock roadway under the mining influence and provide scientific basis for anchor and anchor cable supporting technology, the paper took soft rock roadway under the mining influence as example, which located on Gaojialiang coal mine in Erdos, Inner Mongolia. It used the combined site test methods of hole wall review and earthquake wave reflection, furthermore applied fractal theory to forecast the size of released circle of surrounding rock. The site test results indicate that the size of released circle is a constantly extended process under the mining influence, and the final range is from 1.7 to 1.9 meters, the predicted results accord well with field test using fractal theory. Therefore, the combined test methods can provide a basis for the selection of soft rock roadway support parameters and supply a new testing method of released circle for the other similar coal mine.