Parallel drainage systems occur on the slopes soon after a mountain has been formed.Along with the retrogressive erosion of rivers,drainage divides are migrating. Drainage systemsadapt to their inner and outer dynamics and develop into various types. Some rivers are capturing each other during the development of the drainage systems. There are two crucialcauses of the river capturing. One is the rapidly retrogressive erosion of the capturing river.The other is the suberosion and mass movement under the river beds of the pirated rivers andthe ancient drainage divides. The ancient higher pirated rivers were located at the oppositeside of the ancient drainage divide. Haizihe, one of the branches of the Jianjiang River,canbe taken as an example of river capturing. It captured ancient Huayuangou River (since disappeared) and Yinchanggou River(former right branch of the Shitingjiang).