Dry-wet separation bag for piston

The utility model relates to a piston dry-wet separation bag which comprises a bag body, a containing cavity is formed in the bag body, the bag body is connected with a separation film used for dividing the containing cavity into a first cavity and a second cavity, the bag body is provided with an opening and closing assembly, the circumferential direction of the opening and closing assembly is connected with the bag body, and the opening and closing assembly is fixedly connected with the separation film. The opening and closing assembly is used for communicating or closing the first cavity and the second cavity. The essence and the mask cloth can be loaded in the first cavity and the second cavity in the bag body respectively, the first cavity and the second cavity of the opening and closing assembly do not communicate with each other before a user uses the mask, the essence is prevented from being mixed with the mask cloth, and therefore the activity of the essence is kept; an operator forces the opening an