The utility model provides a be used for cooling off device of culture medium, it is used for placing the frozen water to hold the chamber, the top cap, on the top cap shaping have with hold the chamber number unanimous, and can be deep enough hold the recess in the chamber, the recess is used for holding the culture medium. In the use, at first put into the recess with a plurality of culture mediums or culture medium testing cassette, the recess is as the container, then among deepening holding the chamber with the recess, owing to put the frozen water in holding the chamber, consequently cancarry out cooling treatment to a plurality of culture mediums or culture medium testing cassette simultaneously. Simultaneously, because a plurality of groups culture medium goes on, consequently canimprove the experiment precision effectively under same experiment condition.