A top lining fixing structure comprises a top lining, the upper portion of the top lining is provided with a buckle installation part, and the upper portion of the buckle installation part is provided with a first assembly notch; the top cover cross beam is provided with a second assembly notch; the upper portion of the top lining fastening buckle is detachably clamped to the second assembly notch, and the lower portion of the top lining fastening buckle is detachably clamped to the top end first assembly notch. The top lining fastening buckle comprises a bottom plate and is inserted into the buckle mounting part; the lower ends of the vertical supporting strips are integrally formed in the middle of the upper surface of the bottom plate. The middle of the lower portion of the top plate and the upper ends of the vertical supporting strips are integrally formed, and the top plate is clamped into the second assembling notch. The width of the lower portion of the vertical supporting strip is smaller than the length of the first assembling notch, and the thickness of the top plate is smaller than the width of the second assembling notch, so that the tolerance between the lower portion of the vertical supporting strip and the first assembling notch is large, the tolerance between the top plate and the second assembling notch is large, tolerance superposition is conducted on the top lining and the top cover beam, and the top lining is not prone to damage after being assembled. Meanwhile, the top lining surface sinking problem is avoided.

一种顶衬固定结构，包括顶衬，其上部具有卡扣安装部，卡扣安装部的上部设有第一装配豁口；顶盖横梁设有第二装配豁口；顶衬紧固卡扣的上部可分离地卡接于第二装配豁口，顶衬紧固卡扣的下部可分离地卡接于顶端第一装配豁口；顶衬紧固卡扣包括底板，并插于卡扣安装部的内部；竖向支撑条的下端一体构成于底板的上表面中部；顶板的下面中部和竖向支撑条的上端一体构成，顶板卡接于第二装配豁口的内部；竖向支撑条的下部宽度小于第一装配豁口的长度，顶板的厚度小于第二装配豁口的宽度，以使得竖向支撑条的下部和第一装配豁口容差大，以及顶板和第二装配豁口容差大，用于顶衬和顶盖横梁公差叠加，顶衬被装配不易损坏，同时避免顶衬表面凹陷问题出现。