A fluid compressing system includes: a rotary compressor including a housing defining an oil chamber and an oil-releasing port in fluid communication with the oil chamber; a discharging pipeline connected to the housing for passage of a high pressurized fluid therethrough; an oil-adjusting tank connected to the discharging pipeline and the oil-releasing port for receiving lubricant oil from the oil chamber so as to alleviate oil swirling in the oil chamber; an oil filter connected to the discharging pipeline for separating the lubricant oil from the high pressurized fluid; and a first capillary connected to the oil filter and the housing for recycling filtered lubricant oil from the oil filter into the oil chamber.