The complicated seepage flow field of a pumped storage power station project was simulated by 3D finite element refined simulation technology, the distribution characteristics of surrounding rock seepage field was studied in detail under lining cracks of the high pressure tunnel. The results show that the comprehensive measures for water tight curtain and drainage holes in downstream side of tunnel is effective under cracking hydraulic tunnel, so the seepage field can be controlled to reach up to the requirements, and the safety of the powerhouse is ensured in operating period.