The TIN of river channel is the base of the digital terrain,and is the precondition of quantitative analysis for riverbed evolution and river regime.The digital method of building TIN is researched here,then the distorting triangles causing the TIN inequality and disaccorded terrain are analyzed,finally a new method for building the TIN of river channel is put forward.Through the experiment of building the TIN of Zhenyang reach of Yangtze River,it is showed that the problems above-mentioned are solved effec...