Comprehensive detection technologies are applied in this research to detecte crack leakage of a concrete gravity dam. The leakage inlet is detected by using pseudo-random flow field method, and the range of leakage channel is located by drilling and drilling test technologies including temperature logging, acoustic logging, borehole television observation, water pressure test, and so forth. Results demonstrate that: 1) pseudo-random flow field method could precisely delineate the scope of leakage inlet in the dam in the presence of obvious leakage outlets; 2) cracks in the dam body generally distribute vertical to the direction of the dam body (such as connecting transverse joints) or along the direction of the dam body (such as horizontal joints), or both of them are connected; 3) drilling on dam crest and borehole test method are effective in identifying the elevation and pile number distribution range of leakage channel. The comprehensive detection methods integrating pseudo-random flow field method and borehole testing technology are accurate, rapid, convenient, and safe in detecting the crack leakage of concrete dam, thus can be taken as reference for similar engineering problems.