Abstract: This paper establishes the boundary element integral equation describing the influence of cavity on wave-field scattering in semi-unlimited saturated soil, based on Biot's theory of saturated soil and boundary features of cavity. By introducing the potential function and Betti's reciprocal theory, the singularity of the boundary integral equation was discussed. The effect of saturated soil features and incidence wave field on dynamic stress concentration and pore pressure concentration coefficient was analyzed. The correctness of the algorithm was validated by comparing the values acquired in this study with known literature results. The numerical result indicates that the coupling degree between fluid and solid in saturated soil as well as compression and permeability have great influences on wave-field scattering. As the coupling degrees of the fluid and solid phases in saturated soil increase, the dynamic stress concentration coefficient increases and the cavity scattering effect is strengthened. As the compression of saturated soil decreases, the dynamic stress concentration coefficient increases. As the permeability of saturated soil decreases, the dynamic stress concentration coefficient and pore pressure increase.