The invention belongs to the technical field of mosquito and fly killing and discloses a mosquito and fly killing device comprising a rear faceplate, a side faceplate and a front faceplate for being clamped on a picture frame, a mirror frame or a photo frame. The side faceplate is connected with the rear faceplate and the front faceplate, and the front faceplate comprises a sponge layer, a protection layer, a mosquito and fly attracting layer, a separating layer and a mosquito and fly killing layer; a battery is arranged, the mosquito and fly attracting layer is of a random metal grid structure, the top and the bottom of the mosquito and fly attracting layer are connected with an anode and a cathode of the battery respectively, the separating layer is an insulating layer, and the mosquito and fly killing layer is a metal wire array which is in parallel arrangement and anode-cathode spaced. The mosquito and fly killing device is nontoxic, harmless, safe and environment-friendly, and manual participation is not needed in the mosquito and fly killing process, so that labor force can be emancipated; secondary investment is not needed, so that mosquito and fly killing cost is lowered; more importantly, the mosquito and fly killing device has a brain wave trapping function, thereby being high in mosquito and fly killing efficiency.