The experiments of one-stage semi-circular and two-stage semi-circular impinging stream drying as wellas the vertical and semi-circular combined impinging stream drying were carried out. The velocity distribution andthe mean residence time of particles, and the influence of various factors on drying characteristics were studied. Amathematical model of granular material drying in a semi-circular impinging stream dryer was proposed, in whichthe flow characteristics as well as the heat and mass transfer mechanisms were considered. Reasonable numericalmethods were used to solve the equations. Under various conditions, the calculated results agree well with theexperimental data. The unsteady-state drying dynamic equation, as well as the variations of drying rate andmoisture content versus time were obtained. The results indicate that constant drying rate period does not existin a semi-circular impinging stream dryer. Appropriate semi-circular stage number and curvature radius, flow-rateratio, air velocity, and higher inlet air temperature should be used for enhancing the drying process.