The invention provides an aero-engine and a fan blade thereof. The fan blade comprises opposite blade basin walls, a blade back wall and an inner cavity defined by the blade basin walls and the bladeback wall, a continuous polygonal unit is arranged in the inner cavity, at least a part of the polygonal unit has independent cell walls, and gas film damping structures are arranged between every twoadjacent independent cell walls of at least a part of the polygonal unit, between the cell walls of at least a part of the polygonal unit and the blade basin wall, and/or between the cell walls of atleast a part of the polygonal unit and the blade back wall.