A ducted propeller of a large stout ship operates in the non-uniform wake. Therofore, on such a ducted propeller, there exist many practical problems which are not only in propulsive performance but also in cavitation erosion, vibration forces and so on. However, very sophisticated calculations using the unsteady lifting surface theory are necessary for the exact analysis of these problems and this does not seem to be practical. From this point of view, the author has attempted to analyse these problems by a simple calculation method based on a bold assumption. In this paper, as the first part of the analytical approach, calculations on the flow around a symmetric ducted propeller in the uniform wake are described.