a preservation container cover includes a flexible film to contact with the rim of the container , an upper sealing ring , and a lower sealing ring affixing a periphery portion of the flexible film . the upper sealing ring has a ring slot extending along the periphery portion of the flexible film . the lower sealing ring comprises a ring plug along the periphery portion of the flexible film . the ring slot and the ring plug form a clamp structure to affix the flexible film . the present invention is convenient to use , adaptable to various containers of different types and sizes , and won &# 39 ; t cause waste of natural resources and environment problems .