Abstract: According to the synthesis information of geological environment condition and the data determined by isotope tracer and natural tracer analysis that include hydrogeochemistry condition of Beijiang river dyke leakage, the reason of leakage and infiltration distortion of the dyke in the past years is the existence of some concentrated seepage passageways in the rock. Tracer communicating test by borehole identifies there are two seepage passageways existed in the rock and they are developing further.