The invention relates to a motorcycle oil tank. The motorcycle oil tank comprises an oil tank body, a negative-pressure diaphragm type oil switch which is mounted at a mounting hole formed in the lower end of the oil tank body, an oil level induction device and an alarming circuit, wherein an ejection pipe, which is located in the oil tank body, is further arranged at the top of the negative-pressure diaphragm type oil switch; the oil level induction device comprises a reed switch and a floater; the reed switch forms a switch on the alarming circuit and is used for controlling switching-on/off of the alarming circuit; the reed switch is mounted in the ejection pipe, and the ejection pipe is a copper pipe; the floater movably sleeves the ejection pipe and can be hoisted along the liquid level of the oil tank body; the floater is further provided with a magnetic ring; and the magnetic ring can move along the floater and is used for controlling switching-on or switching-off of the reed switch. The invention aims at providing the motorcycle oil tank, a structure of the oil level induction device is reasonably set and an assembling position of the oil level induction device is reasonably set, so that the oil leakage risk of the oil tank body can be reduced and the assembling efficiency of the whole oil tank can be improved.