A press-to-open sealing cover and a sealing box. The press-to-open sealing cover comprises a top cover body (1), a bottom cover body (2), a pressable member (3), a sealing member (4), and a transmission mechanism (5). The top cover body and the bottom cover body are movably arranged relative to one another, the pressable member is slidably arranged on the top cover body in the axial direction, the sealing member is arranged on the bottom cover body, one end of the transmission mechanism is connected to the pressable member, and the other end of the transmission mechanism is connected to the bottom cover body. Pressing the pressable member drives the transmission mechanism to drive the bottom cover body to move in the axial direction relative to the top cover body, so as to drive the sealing member to move. According to the press-to-open sealing cover, the pressable member is linked with the bottom cover body by means of the transmission mechanism, and pressing the pressable member drives the transmission mechanism to drive the bottom cover body to move in the axial direction relative to the top cover body, to thus drive the sealing member to move. For a user, the state of the sealing cover can be changed by simply pressing the pressable member, and the opening and closing of the cover can be easily, effortlessly, and conveniently completed with one hand.