The invention belongs to the technical field of biological experiments, and particularly relates to a flattop PCR tube cover pressing device used in laboratories. The device is composed of a holding handle, a rolling wheel, an extrusion ring and an extrusion ring locking screw pin, wherein a U-type groove is formed in one end of the holding handle, the rolling wheel is fixed in the U-type groove, the extrusion ring is composed of a plurality of arc blocks which are arranged at intervals and is arranged at one end of the holding handle, and a cylindrical body is arranged on the middle part of the holding handle; the rolling wheel is of a cylindrical structure, the height of the cylindrical structure is smaller than the diameter of a PCR tube cover, and the arc-shaped face of the cylindrical structure is provided with a plurality of annular ridge lines parallel to the side of the cylindrical structure. The flattop PCR tube cover pressing device used in laboratories can be used for pressing flattop PCR tubes in large batches or a single flattop PCR tube and widely applied to teaching and scientific research activities in the biological laboratories, particularly in laboratories where PCR reaction need to be performed in large batches. The device is easy to operate, it is guaranteed that all covers of the flattop PCR tubes in large batches are pressed in a short time, and working efficiency is greatly improved.