Waterproof door assembly of electronic device

A waterproof door assembly of an electronic device, and the electronic device having an opening and an annulus wall disposed around the internal periphery of the opening, comprising:

• a fastening element, formed on the electronic device;
• a waterproof door, comprising:
• a door panel, pivotally coupled to the electronic device, and disposed at a position corresponding to the opening, and having a bump and an engaging portion extended from two opposite sides of the door panel respectively;
• and
• a replaceable ring, sheathed on the periphery of the bump;
• and
• a switch flipping element, coupled to and slid on the door panel, and having a snapping portion and a fastening portion, such that the switch flipping element can be slid to drive the snapping portion and the engaging portion to perform a multi-stage position adjustment, so as to latch the fastening portion to the corresponding fastening element, and the bump is inserted into the opening, the replaceable ring is clamped between the annulus wall and the bump.