A far-field numerical model is developed to simulate jet pollution into natural rivers. Its character is to compute the velocity and pollution concentration separately. The velocity is computed by SIMPLEC algorithm in boundary-fitted coordinate systems. The pollution concentration distribution is computed by developed QUAL-IIm and QAIIL 2D program. The present model was applied to the Xiantao section of the Hanjiang River a tributary of Yangtze River, and Xiangjiang River. The flow field and COD distribution are in good agreement with field data.