The invention provides a device for trapping, classifying and counting orchard flying injurious insects. The method comprises a solar panel, a trapping device, a rainwater treatment device, a counting device, a collection device, a preprocessing device, a classifying device, a recycling device and a master control panel, wherein the trapping device is used for attracting and killing the injurious insects according to gyplure. The counting device comprises a first group of infrared sensors which include four orthogonal photoelectric sensors arranged in an orthogonal mode, connected in a mode of a Chinese character 'huo' (or) and connected to the same input / out (IO) port, and the counting device counts the injurious insects according to level changes of the IO port. The collection device comprises three groups of orthogonal infrared photoelectric sensors, namely, a second group of infrared photoelectric sensors, a third group of infrared photoelectric sensors and a fourth group of infrared photoelectric sensors, wherein each group of infrared photoelectric sensors include four infrared photoelectric sensors, the distances between every two groups of infrared photoelectric sensors are the same, and the collection device is used for calculating the length of the injurious insects.