This paper is concerned with the development of a method for calculating the hydrodynamic characteristics of marine propellers in a viscous fluid. Firstly, the characteristics in a non-viscous fluid are calculated by applying the propeller lifting surface theory and at each propeller section, a so-called corresponding two-dimensional wing which has the same hydrodynamic property and geometrical thickness distribution as the corresponding propeller section, is derived from the calculated circulation distribution. Then circulations corrected by the effects of viscosity and drag coefficients of propeller sections are obtained by using calculated boundary layer properties of the corresponding two-dimensional wings. Finally, the propeller characteristics in a viscous fluid can be obtained from these circulations and drag coefficients. Calculated results of propeller performances are compared with open-water test results and agreement between calculation and experiment is good. Also scale effects of propeller performance are examined by this method.