The invention relates to an oil pumping device, specifically to a valve core structure oil pumping device for a one-step-start carburetor. The valve core structure oil pumping device comprises a support, a valve core, an oil pumping chamber, a magnetic valve and a lower cover. When the oil pumping device works, sucking pulses are produced in the oil pumping chamber to suck fuel oil in an oiler into the carburetor to provide fuel oil for the carburetor and blowing pulses are produced in the oil pumping chamber to blow redundant fuel oil in the carburetor into the oiler through surging force of blowing pulses. The valve core structure oil pumping device omits an oil pumping ball of the carburetor using the prior art, thereby users do not need to pump oil by pressing the oil pumping ball with hands before an engine starts. The fuel oil in the oiler is pumped in the carburetor through the valve core structure oil pumping device so that the engine can easily suck out the fuel oil from a measuring room of the carburetor when starting, and the fuel oil squirts from a nozzle of a main jet to achieve normal start of the engine eventually.