Abstract: Embodiments of the present application provide a hole array layered structure, a precoating method, a membrane forming method and a sequencing device. The hole array layered structure is adapted for forming a membrane forming space with a substrate, wherein the membrane forming space is adapted to form a membrane layer. The hole array layered structure includes a base plate, a plurality of hole units is provided in the base plate in an array, each hole unit penetrates through the base plate and includes a first hole and a second hole stacked in a thickness direction of the base plate, a first hole contour of the first hole surrounds a second hole contour of the second hole on an outer side thereof, the second holes of the plurality of hole units are disconnected with each other, and the first holes of the plurality of hole units are disconnected with each other.