Connection fitting and protection window net

The invention relates to a connection fitting and a protection window net. The fitting comprises an adjusting block, an adjusting bolt and a buckling assembly. The adjusting bolt and the adjusting block are connected and arranged in a corner connector of a frame. When the adjusting bolt is rotated, the adjusting block abuts against and pushes a frame pipe end opening of the frame to drive the size of the frame to be enlarged, or the adjusting block moves towards the interior of the corner connector to drive the size of the frame to be decreased. The buckling assembly is connected with the frame and buckled with a window flange of a building window. The protection window net comprises a protection steel frame, a mosquito prevention gauze element, magnetic joint strips and the connection fittings, wherein the magnetic joint strips are arranged along a frame of the mosquito prevention gauze element, the mosquito prevention gauze element is attracted to the protection steel frame through the magnetic joint strips, the connectors are connected with the protection steel frame, and when draw-in bolts are screwed, the window flange is buckled by the buckling pieces, and the protection steel frame is driven to be closely attached to the edge of the window. The connection fitting and the protection window net have the beneficial effects that the structure is simple, mounting is convenient, field adjustment and adaptation can be achieved, and cost is reduced.