The invention discloses an abnormal event detection method based on a fixed-position camera monitoring video, and the method comprises the steps: A, obtaining a frame of image shot by a camera under the normal condition, calibrating an invariant region, and enabling the image of the invariant region to serve as an initial reference image; B, acquiring a real-time image shot by the camera after a preset sampling interval time, and extracting an image of an invariant region of the real-time image as a judgment image according to the invariant region; C, comparing the similarity between the judgment image and the reference image, if the similarity is within a preset normal similarity range, replacing the current reference image with the judgment image, and then turning to the step B; Otherwise, judging that an abnormal event occurs. The invention further discloses an abnormal event detection device based on the monitoring video of the fixed-position camera. According to the invention, themethod can achieve the accurate and automatic recognition of the interference of the camera and the abnormity in a monitoring scene, is better in accuracy and real-time performance, and is low in software and hardware requirements.