Aiming at the characters of high ground stress and high pore water stress, which resulting in water invasion risk in excavation of subsea rock, FLAC is adopted to simulate the strain localization phenomena of surrounding rock with different pore water pressure and confining pressure. In calculation, the strain soft constitutive relation and “first loading then unloading” pattern are used. Simulation result states that, the bigger the confining pressure is the more destruct the surrounding rock is, and the water invasion risk is more serious. In high confining pressure condition, shortly after excavation, the destroy zone is thin ring, subsequently, the arc shoulder and arc bottom occurs shallow hole, the destroy zone increasing, which presents zonal disintegration. Pore pressure has obvious influence at plastic strain of rock, the high pore water pressure results in surrounding rock destroy zone enlarging, which changing the seepage field of rock, and probably lead to seepage instability.