The invention discloses an illegal dog walking event detection method based on a monitoring video, and the method comprises the following steps: A, carrying out the detection of a dog and a person in an image frame, and judging that the state is normal if no dog is detected, and returning; if no dog exists, judging that the dog is not tied with the rope and returning; otherwise, entering the step B; step B, estimating the distance between the person and the dog and judging whether the distance exceeds a distance threshold value or not, if so, judging that the dog is not tied with the rope and returning; otherwise, entering step C; C, intercepting an image containing the dog, inputting the image into the dog rope tying recognition model, and if the output is that the dog is tied with the rope or the dog is not tied with the rope, outputting and returning the result; otherwise, entering the step D; and step D, finding out k persons closest to the dog, intercepting a maximum detection frame image, inputting the maximum detection frame image into the person-dog relation identification model, and judging whether the dog is tied with a rope or not according to model output. The invention further discloses an illegal dog walking event detection device based on the monitoring video.