A ground line structure adapted to a flexible circuit board is provided. The ground line structure includes a plurality of ground line structure units located on the flexible circuit board to form a meshed pattern. The ground line structure units include a plurality of ground line edge segments, a ground line middle segment and a plurality of ground line connecting segments. The ground line edge segments define an edge shape of each ground line structure unit. The edge shape of each ground line structure unit is a hexagon. The ground line connecting segments are configured to connect the ground line middle segment and the ground line edge segments. The ground line edge segments, the ground line middle segment and the ground line connecting segments form a plurality of pentagonal electrode structures within the hexagonal ground line structure unit. A flexible circuit board including the ground line structure is also provided.