The invention discloses a biogas pressure scrubbing and purifying method which comprises the following steps: introducing pressurized biogas into a scrubbing tower, feeding the biogas from the lower part of the tower, spraying water from top to bottom of a tower body in at least two stages so as to remove carbon dioxide and hydrogen sulfide in the biogas, and discharging the product gas outside the scrubbing tower from an exhaust valve, wherein the pressure inside the scrubbing tower is controlled to be 1.0MPa -1.2MPa and the total water flow of all water spraying devices is controlled to be 0.6m<3>/h -0.72m<3>/h. The scrubbing tower is constructed according to the characteristic that the dissolution degrees of carbon dioxide, hydrogen sulfide and methane in water are different via a physical absorption process, and through pressure scrubbing, carbon dioxide and hydrogen sulfide gases in the biogas are removed, so that the product gas meets the requirements of GB18047-200 without needing packing or absorbent; the scrubbing tower is low in pressure, convenient to operate, low in cost, low in energy consumption and free of discharge, the water resource can be saved, and the requirements of national environmental-friendless are met.