Abstract: 2-D water age model by operator-splitting algorithm is developed. The governing equation is splitted into three or two successive initial value problems. In any arbitrary triangle calculation grid, the operators are calculated by different algorithm on the basis of their characteristics. In convection problem, the method of characteristics is used. For the dispersion and propagation problem, a semi-implicit finite element algorithm is employed in the calculation. The model validation is tested by two different ways, including establishing a water transfer physical model and analytic solutions based on the symmetry characteristic of age model. The computed results well agree with the two tests, including velocity, concentration and age. This study can provide technical support for the age model validation.