A model of ion-heating, based on the magnetohydrodynamic (MHD) dynamo, has been proposed. During magnetic reconnection, which is an inevitable process in the MHD dynamo, plasmas can be accelerated to a speed comparable to the Alfven velocity. Using Petschek's expressions for fast reconnection and the configuration of helical reconnection lines, both the dynamo and the ion heating are described by the model. Plasmas gain kinetic energy during the reconnection, and the energy can then be thermalized by ions through viscosity. Simultaneously, toroidal flux is generated and the poloidal flux is consumed. The ion-heating power calculated by the model accounts for about 20% of the total input power in the REPUTE-1 reversed-field pinch plasma. This value of the ratio is consistent with other experimental results.