Abstract: To solve the water treatment engineering of biological filter bed gravel drive technology in the process of application of filter bed scale parameters and different size,different boundary conditions to determine the filter bed with different regional conditions,different degree of pollution of river pollution treatment effect simulation prediction problem,this paper is used as an example in Hanzhong water system based on water quality QUAL2k model to generalize the experimental monitoring results combining the indoor small simulations under different working conditions of gravel filter bed of river water quality purification effect. The results show that the maximum removal rates of NH₄⁺-N,PO₄^3--P and COD of the filter bed at 200 m in summer are 51.5%,54.3% and 54.1%,respectively,which can improve the PO₄^3--P and COD of the controlled cut water to the Class Ⅲ water standard and NH₄⁺-N to the Class Ⅳ water standard. In winter,the removal rates of NH₄⁺-N,PO₄^3--P and COD of the 400 m filter bed are 68.6%,57.5% and 51.1%,respectively,realizing the water quality goal of COD reaching Class Ⅲ water and PO₄^3--P approaching Class Ⅳ water.