The invention relates to doors and windows. A cavity-increasing heat-preserving type door and window sash comprises a door and window profile, wherein the door and window profile is provided with an inner cavity with profile part sealing strip connecting troughs; a plurality of insulating boards are arranged in the inner cavity; the insulating boards divide the inner cavity into a plurality of heat insulating and preserving cavities; insulating board part connecting troughs and outer clamping strips are respectively arranged at two sides of the insulating boards; the insulating boards are clamped in the profile part sealing strip connecting troughs by outer chucks and are connected with the wall of the inner cavity; every two adjacent insulating boards are connected together in a manner that the outer chuck of one insulating board is clamped into the insulating board part connecting trough of the other insulating board; a slide rail assembling opening is formed in one heat insulating and preserving cavity; sealing strips are arranged at two sides of the slide rail assembling opening; the sealing strip at one side of the slide rail assembling opening is clamped in the insulating board part connecting trough, and the sealing strip at the other side of the slide rail assembling opening is clamped in the insulating board part connecting trough or the profile part sealing strip connecting trough. The cavity-increasing heat-preserving type door and window sash provided by the invention achieves sound insulating and heat preserving effects of doors and windows in a cavity increasing manner, so as to improve the heat preserving and sound insulating effects of doors and windows.