The invention discloses a low-back-pressure horizontal compressor and a refrigerating system. The compressor comprises a shell and a compressing mechanism, wherein the shell is provided with an air suction pipe and an air discharging pipe, and a low-pressure oil pool is arranged at the bottom of the shell; the compressing mechanism comprises two air cylinder, two fitted bearings, two cover plates, a crankshaft and a rolling bearing, the cover plates are respectively arranged at the sides, facing to each other, of the two air cylinders, the two fitted bearings are connected through a retainer to define a closed air discharging cavity, the crankshaft is matched with the two fitted bearings, the rolling bearing is arranged between at least one fitted bearing and the crankshaft, the part, which is provided with the rolling bearing, of the fitted bearing is matched with the crankshaft in a sliding manner, a central hole is formed in the crankshaft, a plurality of radial holes are formed in the crankshaft and are communicated with the central hole, the central hole is communicated with the low-pressure oil pool through an oil supplying pipe, and each fitted bearing and at least one radial hole are correspondingly arranged. The compressor provided by the invention is beneficial to increasing oil supplying amount and alleviating the abrasion of the fitted bearings.