Marine nutritive salt online analysis system and control method

The invention relates to a marine nutritive salt on-line analysis system and a control method, the marine nutritive salt on-line analysis system comprises a floating body, the floating body is of a circular ring body structure, the interior of the floating body is divided into an even number of mounting cavities distributed at equal angles through partition plates, and a tilt angle sensor is arranged above the floating body; the plurality of liquid sensors are arranged on the bottom surface of each mounting cavity; the plurality of counterweight systems are arranged in each mounting cavity, each counterweight system comprises a lead screw and a counterweight block, and the lead screws are arranged on the bisectors of the mounting cavities and are used for driving the counterweight blocks to move on the bisectors of the mounting cavities; the driving piece is used for controlling the position of the corresponding balancing weight on the center line of the mounting cavity; the control system receives data of th