The invention discloses a stepless delivery regulation method of reciprocating-piston compressor, which is characterized in that duty cycle is determined using the maximum delivery and the actually required delivery of the compressor under full load; an inhalation valve is forced to open or freely closed through a control system and a or a plurality of executive device (s) for pressing the inhalation valve, enabling load circulation and non-load circulation to be alternatively distributed to comply with the duty cycle, thereby evenly supplying the required delivery. The invention has the advantages of capability of 0 to 100% continuous delivery regulation, less pressure fluctuation, saved energy, lowered noise, simple and reliable regulation effect.