The invention discloses a limit oil level sensor. The limit oil level sensor comprises a shell, a magnetic floater, a miniature oscillator, a reed switch, a buckle and a plug. The shell comprises a connecting body and a slide body. One end of the connecting body and the plug are fixed, and the other end of the connecting body and one end of the slide body are fixed. The magnetic floater sleeves the slide body. The other end of the slide body and the buckle are fixed. The shell is integrally formed and is provided with an accommodating cavity. The miniature oscillator and the reed switch are arranged in the cavity. The reed switch is arranged at the bottom part of the cavity. The miniature oscillator is electrically connected with the reed switch. The accommodating cavity of the shell is also internally provided with fillers used for fixing the miniature oscillator and the reed switch. The plug is electrically connected with the miniature oscillator and the reed switch via connecting lines. The limit oil level sensor is high in detection precision.