The invention relates to a winnowing pan type grain throwing machine. The winnowing pan type grain throwing machine comprises a frame, a grain throwing hood, a throwing motor and an impeller. The impeller is arranged in the grain throwing hood which is arranged on the upper portion of the frame, bearing seats at two ends of the impeller are arranged on the frame respectively, a center shaft of the impeller is connected with an output shaft of the throwing motor through a coupler, and the center shaft, the coupler and the output shaft are coaxial. The grain throwing hood is provided with a feeding port and a discharging port, and blades of the impeller are bent plates. The winnowing pan type grain throwing machine has the advantages of small size, stability of grain throwing paths, low noise, detachability of parts, convenience in installation and maintenance, low cost and flexibility in use.