The invention discloses a pilot-operated type servo cartridge valve driven by low-power servo motor and a closed-loop control method of the pilot-operated type servo cartridge valve. The cartridge valve uses a control screw and a guidance key to convert the rotary motion of the low-power servo motor with high response and high positioning accuracy into the reciprocating motion of a control valve spool and realizes the closed-loop control through the mechanical displacement feedback, so that the same direction and same distance motion is formed between the control valve spool and a main valve spool to enable a primary valve to remain open and in an equilibrium state under the dynamic closed-loop control of the servo motor and a servo controller. In general, the pilot-operated type servo cartridge valve driven by low-power servo motor utilizes the high response and high positioning accuracy of the low-power servo motor to achieve the high response and high control accuracy of the servo cartridge valve, and adopts the mechanical displacement feedback in entire process to realize the closed-loop control, therefore the control cost is low and the accuracy and the stability are high.