Numerical analysis has been performed for the developing turbulent flow in compound meandering open-channel flow by using algebraic Reynolds stress model. The turbulent flow in compound meandering channel is one of the complicated turbulent flows, because the flow behavior is influenced upon many kinds of forces that are centrifugal force, pressure driven force and shear stress generated between main channel and flood plain. In order to set precisely boundary condition along complicated configuration, the boundary fitted coordinate system has been introduced in this analysis so that transport equations are transformed from the physical plane to the calculation plane. As a result of this calculation, it has been found that the present method is able to predict well the mean velocity distribution and the developing pattern of secondary flow that is especially affected by the flow over the flood plain. As for the comparison with Reynolds stresses, although the agreement with the experimental data is not perfect quantitatively, the present method is able to reproduce the characteristic features.