Single-blade centrifugal pumps with a screw-shaped blade are widely used to pump slurry water containing solids and fibrous matters. These hydraulic machines should be frequently used, because of their suitable hydraulic and mechanical properties, in many industrial areas. There cannot be applied a conventional method to design a single-blade impeller, due to its lack of symmetry. The designing of an impeller, which enables fulfilled main requests such as good hydraulic, mechanical properties and the ball passage diameter as well as the influence of the blade outlet angle on hydraulic parameters is described in this academic paper.