Constant-temperature water bath kettle with adjustable water bath hole diameter

The constant-temperature water bath kettle is characterized in that a plurality of water bath holes are formed in the top surface of a water bath box, blocking pieces made of elastic materials are arranged in the water bath holes, the outer edges of the blocking pieces are connected with the hole walls of the water bath holes, and partition notches penetrating through the blocking pieces are formed in the blocking pieces; a limiting device capable of vertically stretching out and drawing back is arranged over the water bath hole and comprises a clamping assembly, a stretching assembly and a base, the clamping assembly comprises a clamping rod, a circular ring, a limiting rod and a check block, one end of the clamping rod is fixedly connected with the top end of the stretching assembly, the other end of the clamping rod is fixedly connected with the circular ring, and a first through hole is formed in the outer wall of the circular ring; one end of the limiting rod penetrates through the first through hole and