The invention relates to the technical field of hydraulic valves and discloses a high-sensitivity pilot overflow valve. The device comprises a pressure relief channel, a pilot valve cavity and a pilotpressure regulating spring, wherein two oil distribution channels are arranged at the top end of the pressure relief channel, and the two oil distribution channels both communicating with an inner cavity of the pilot valve cavity; an ejector rod is arranged inside the pilot valve cavity, a direct-acting valve core, a hole plug and a supporting piece are fixedly sleeved with the ejector rod in sequence from left to right, and a direct-acting pressure regulating spring is arranged at the other end of the direct-acting valve core; and a pressure relief hole is formed in the position, at the direct-acting valve core, of the top end of the pilot valve cavity, and the pressure relief hole is used for communicating the pilot valve cavity with a hydraulic system oil tank. According to the high-sensitivity pilot overflow valve, the direct-acting valve core and the hole plug are additionally arranged in the pilot valve cavity of an original pilot overflow valve, so that under the condition thatpressures controlled by the direct-acting pressure regulating spring and the pilot pressure regulating spring are the same, the high-sensitivity pilot overflow valve is capable of not only controlling sensitivity at a position of the direct-acting valve core but also controlling pressure stabilization at a position of a main valve core, and has wider application fields.