The invention discloses a marine benthos on-site automatic shooting and measuring device which comprises a movable support and a vertical rod. The movable support is provided with a sample frame, the vertical rod is provided with a shooting end which is provided with an underwater camera, the shooting end penetrates through a clamping ring at the upper end of the movable support and then is placed above the sample frame and can be used for adjusting the distance between the underwater camera and the sample frame, and the underwater camera is in line connection with a shooting processing system arranged outside the movable support. The movable support is arranged and provided with the underwater camera, and therefore when an underwater sample is shot, the movable support is arranged on a survey station and located underwater to observe benthos in the sample frame, the vertical rod is used for adjusting the distance between the underwater camera and the sample frame, the underwater camera is used for shooting and recording the conditions of the sample and sending images to the shooting processing system, and therefore the types and the quantity of the benthos in the sample frame can be conveniently counted, sample data can be collected automatically, and the shooting processing system can be connected with a rechargeable storage battery. The device is suitable for measurement on the sea.