The present invention provides a substrate fitting process and a substrate assembly to be fitted, wherein the substrate assembly to be fitted of the present invention, a periphery mold frame is disposed on a surface of a substrate, a cell mold frame is disposed inside said periphery mold frame, the height of said cell mold frame is larger than the height of said periphery mold frame. A substrate fitting process of the present invention comprises: providing a cell mold frame on a surface of a first substrate, providing a cell mold frame inside the periphery mold frame for sealing liquid crystal, the height of said cell mold frame is larger than the height of the periphery mold frame; extracting the air between the first substrate and the second substrate; making the first substrate fit with the second substrate preliminarily; filling the air between the first substrate and the second substrate; making the first substrate further fit with the second substrate. With the technical solution of the present invention, the puncture caused by the impact of the in-cell liquid crystal onto the cell mold frame is prevented, and the time and the costs of the process is decreased, meanwhile the probability of the circuit metal wire and the component switch on the liquid crystal panel suffering corrode of the thinning acid is decreased.