The invention discloses a three-section type idle metering jet which comprises a foam pipe, an adapting pipe and a metering jet pipe, wherein the foam pipe is encapsulated in the adapting pipe throughthe metering jet pipe; an idling channel is formed in the metering jet pipe; an oil gas channel is formed in the foam pipe; the passageway cross section of the oil gas channel is greater than the minimum passageway cross section of the idling channel; the adapting pipe comprises an upper cavity and a lower cavity; the first end of the foam pipe is positioned in the lower cavity; the second end ofthe foam pipe stretches out of the top of the upper cavity; the first end of the metering jet pipe is in threaded connection with the inner wall of the lower cavity; the idling channel communicates with the oil gas channel; the internal diameter of the upper cavity is greater than the external diameter 0.8-1.4mm of the foam pipe; and a plurality of foam holes are formed in the side wall of the foam pipe and are formed in the upper cavity. The three-section type idle metering jet is simple to manufacture and low in cost and can store fuel to provide sufficient fuel for a carburetor when an engine is started, so that the concentration of mixed gas of the carburetor is increased, and the problem that the engine is difficult to start is also solved.