Abstract: A liquid level measuring device includes a container and a digital electronic device. The container is located at a detection region. The container has an opening, so that a liquid is permitted to flow into the container through the opening. The digital electronic device is combined with the container. The digital electronic device includes a lens, and an optical axis of the lens is directed to and perpendicular to a detection plane. A light source illuminates the detection plane. The lens is operated in a fixed-focus mode to shoot the detection plane to acquire an image stream. Each image frame of the image stream contains a corresponding liquid surface image. After an image analyzing operation is performed on the corresponding liquid surface image to calculate the corresponding liquid surface image, a liquid level of the liquid is realized.