The invention relates to a non-contact electrocardiogram sensor, which adopts a round double-side printed circuit board (PCB) electrode, wherein three regions are arranged on one side, the three regions are in an electric insulation state, the center round region is a sensing sheet, an annular shielding region and an annular ground wire region are in sequential arrangement towards the outside, three regions are also arranged on the other side, the center round region is a copper covering region, a patch welding region comprising a prepositive operation amplifier and a front end filter is arranged in the center of the copper covering region, the outer periphery of the copper covering region is the annular ground wire region, the region simultaneously occupied by the sensing sheet and the adjacent annular shielding region is symmetrical to the copper covering region arranged on the other side, the annular ground wire regions arranged on the two sides are symmetrical, the output end of the prepositive operation amplifier is respectively connected with the annular shielding region and the copper covering region, the ground end of the prepositive operation amplifier is respectively connected with the annular ground wire regions arranged on the two sides, and the input of the prepositive operation amplifier is connected with the output of the sensing sheet. The double-side PCB electrode is positioned at the open opening end of a metal shielding box, the side provided with the sensing side faces the open opening, and the side provided with the copper covering region faces an inner cavity of the shielding box.