In order to improve controllability of mixed-flow pump performances during the design process, effects of exit circulation distribution on design of mixed-flow pump impeller were researched. Based on three-dimensional inverse design theory, the meridional derivative of circulation Vur was chosen for the control parameter of blade loading distributions. Three impellers were designed, whose exit circulations were respectively averaged-loaded, rising-loaded and falling-loaded. The RANS equations embedded with SST turbulence model were solved by using multiple-reference-frame model to simulate flow field of the three pumps. The pump efficiency and cavitation, total pressure and meridional velocity at the impeller exit were compared and analyzed. The results show that the rising-loaded pump has the highest efficiency but the worst cavitation performance, and performances of the falling-loaded pump are just on the contrary. The three-dimensional inverse design theory with adjustable exit circulations can effectively adjust the work abilities at different blade heights. Both the total pressure and meridional velocity at the rising-loaded impeller exit the rapidest increasing velocity with the radius rising.