The invention relates to a cross fold line type slotted wideband uniplanar compact electromagnetic band gap UC-EBG structure and a design method thereof, and belongs to the electromagnetic transmitting and receiving technology field. The UC-EBG structure has characteristics of wide band and adjustable band gap. The parallel reflection band gap of the CFL-UC-EBG is in a range from 63 to 935 GHz, and the relative bandwidth is 38.85%. Based on the same structure, by changing a structure unit number, when three CFL-UC-EBG structure units are in a periodic arrangement, the UC-EBG structure having the forbidden band gap in a range from 50 to 80 GHz and the relative bandwidth of 46.15% is acquired. The CFL-UC-EBG provided by the invention is widely used for 60GHz high frequency microwave antennas.