A grain sorting and counting device relates to the technical field of grain counting machines, and comprises a base and a screening box. A screening box support fixedly supports the screening box in a front space of the base. A combination of the base and the screening box is approximately rectangular parallelepiped. A motor and a photoelectric sensor are mounted in a rear end space of the base. One side of the photoelectric sensor is provided with a grain rolling-down rail. The base is a supporting bearer of the whole device. The motor is a power source of the whole device. An output end of the motor is connected with the screening box, and provides power for the screening box. The screening box sorts the grains one by one. The grain rolling-down rail is a channel on which the grains slide down, and limits a movement track of the grains, so that the grains can pass an area detected by the photoelectric sensor. The photoelectric sensor is a core component for counting, and provides a reverse voltage pulse when a grain passes. A CPU on a circuit board of the photoelectric sensor calculates the number of grains according to changes of pulses. The grain sorting and counting device disclosed by the present invention has a small overall volume, so that a large number of the devices can be assembled to form an integral structure.