A flexible circuit board includes an insulating layer, a linear signal line, a plurality of grounding lines, a metal coating layer, a circuit layer and an electromagnetic shielding layer. The insulating layer includes a first face and a second face. The metal coating layer covers the linear signal line on the first face. The metal coating layer has a thickness less than that of the linear signal line, and an electrical conductivity larger than that of the linear signal line. The grounding lines are at two opposite sides of the linear signal line on the first face. The circuit layer is on the second face. The electromagnetic shielding layer covers the linear signal line and the grounding lines. The linear signal line and the grounding lines are between the electromagnetic shielding layer and the circuit layer. A method for manufacturing the flexible circuit board is also provided.