A substrate assembly including a first substrate, a second substrate, a sealant, and a blocking structure is provided. The first substrate has an active area. The sealant is disposed between the first substrate and the second substrate. The sealant assembles the first substrate and the second substrate and separates the first substrate and the second substrate in a cell gap to define a space, wherein the sealant has an injection opening. The blocking structure is disposed on the first substrate and located outside the active area. A distance from the blocking structure to the second substrate is smaller than the cell gap, wherein the blocking structure divides the space into a first area and a second area. The injection opening is merely located inside the first area and the active area is merely located inside the second area.