The similar materials is used to simulate the soft rock-mass on the basement of tunnel in the high speed railway. Based on the method of loading control and the cyclic loadings of non-symmetrical sine wave, the dynamic fatigue test of three axial and the damage detection test are carried on for soft rock-mass specimens. With analysis of the results of tests,the polynomial model with three parameters to calculate the fatigue life and the polynomial model with four parameters to calculate the cumulative damage are established for soft rock-masses. And then, some characteristics of fatigue damage has been obtained about the soft rock-mass, such as the fatigue failure of soft rock-mass mainly shows two composite modes those are the tension-shear on the end and the compression-shear on the central of specimen. The whole process of fatigue damage is shown three stages those are the compaction of initial micro-pore, the occurrence and stable propagation of new cracks,and the accelerating development of crack damage. The fatigue life of soft rock-mass mainly depends on itself strength and the level of dynamic stress. The higher strength of itself and the lower level of dynamic stress,the longer fatigue life of rock-mass will be. If the level of dynamic stress has not been changed, the fatigue life of soft rock-mass will be increased linearly with its elastic model.