Insect prevention device at top of greenhouse

The utility model relates to an insect prevention device at the top of a greenhouse. A plurality of brackets are fixedly arranged in parallel in the top of the greenhouse; the bottoms of the brackets are saw-toothed; a main moving rod and a plurality of auxiliary moving rods are vertically arranged on the brackets; a support block is fixedly arranged on the main moving rod; the brackets penetrate through the support block; the main moving rod moves on the brackets through the support block; the end part of the main moving rod is connected with a motor and a control device; the main moving rod fixes one edge of an insect prevention net through a clamping buckle; and the auxiliary moving rods are slidingly connected with the brackets by a roller. The insect prevention device is simple in structure and convenient to operate, can ensure ventilation inside and outside the greenhouse, and can prevent insects from entering the greenhouse and damaging crops in the greenhouse.