The present invention relates to the technical field of seawater detection, in particular to a detection and alarm device for mariculture, comprising a mounting plate, the upper end of the mounting plate is provided with a motor, the output shaft of the motor is mated and connected to the winch, the mounting plate The lower end of the plate is also fixedly connected with a vertical rod, the side end of the vertical rod is provided with a chute, and a sliding rod is slidably connected to the chute, and one end of the sliding rod is fixedly connected with a detection box. If the limit rod touches the edge of the upper end of the card hole when it moves downward, it will guide the second limit rod, thereby improving the practicality of the equipment, avoiding the slipping of the belt, and accurately controlling the detection box The depth in the pool, and the detection box can work stably in the pool through the limit component, which improves the practicability of the equipment, and can detect the temperature and pH value of the seawater inside the breeding pool in real time, providing timely and accurate information.