The flow characteristics of two models of cross flow fan were clarified by the flow visualization and LDV investigations. The velocity vector maps, stream lines and vorticity distributions were obtained so that the position of the eccentric vortex in the rotor was clear. Furthermore, the aerodynamic characteristics of a blade and the power generated by a blade were clarified. The results showed that the blades of rotor at 8=240° to 270° (in discharge area) have a good aerodynamic performance and have done the much work than that of the suction area. The effect of changing of casing's shape and suction load in suction area on the flow pattern was also cleared.