A dual fuel carburetor includes a carburetor body, a main jet pipe and a float chamber housing to form a float chamber, the needle valve device includes a pushing needle and a needle valve base, the pushing needle is movably inserted in the float chamber housing, and a window is formed at a bottom of the float chamber housing, the needle valve device further includes a sealed corrugated sleeve positioned around the pushing needle, which has a first end hermetically connected with the pushing needle and a second end hermetically connected with the float chamber housing, a driving spring is positioned around the pushing needle, and the pushing needle has a driving end extended out from the float chamber housing and opposite to that end cooperated with the valve base hole. The needle valve device is in a reasonable design to obtain mechanical controls or other automated drive controls.