Instability characteristics generated with partial flow rate in a mixed-flow pump have bad influence during the pump operation. In this paper, a method to control blade loading distributions of the mixed-flow pump by a simple and easy method is shown. This method was applied to control of the blade loading distribution of the blade tip in mixed-flow pumps. Furthermore, performance and the internal flow of these pumps were examined experimentally. As a result, head and pump efficiency fell at flow rate of the best efficiency in the impeller of aft-loading, but the instability characteristics were largely improved. In addition, a reverse flow suddenly developed at the impeller inlet tip side with the decrease of the flow rate in the impeller of fore-loading, but it was shown clearly that the reverse flow did not suddenly develop in the impeller of aft-loading.