A 1 U connection chassis and a 1 U cabinet, wherein two or more intermediate plates (16) mutually parallel to one another are disposed inside the 1 U connection chassis; each of the intermediate plates (16) is provided with one or more slots mutually parallel to one another; two opposing slots on two adjacent intermediate plates (16) respectively constitute a mounting dock; an adaptor module (18) or a splice tray (19) is slidably inserted into each mounting dock; optical fiber adaptors are mounted inside the adaptor module (18). The chassis has optimized internal mounting space to allow more adaptor modules and/or splice trays to be mounted in the limited mounting space.