Abstract：The caving of thick and strong roof stratum，key stratum，causes tremendous rock pressure in mine. In order to control the rock pressure effectively，the thick and strong roof strata，of which the softening factor is relatively small，can be treated previously by boring and high pressure water infusion，water infusion softening method. With the help of RFPA2D software，the strata behaviors of different parameters，softening factors and softening thickness of the stratum in a mine，are simulated numerically. In the numerical simulation，different values of mechanical parameters of the softened parts of the roof stratum，Young¢s modulus，compressive strength，tensile strength and etc.，are taken for corresponding values of softening factor. Relations between the parameters and softening effect are studied. The first caving distance and rock pressure of overlying strata decrease as the softening factor decreases and the softening thickness increases. For practical mining engineering，the two parameters have to obtain some certain values to realize good roof control. There are some mining faces，where though the rock can be softened by water infusion，geological condition of a mine and mining technology makes the using only of water-infusion softening method not very effective，other methods，or combined with water-infusion softening method，should be adopted.
