The present invention provides a non-contact pulley liquid level sensor, comprising a float capable of floating up and down and floating on a liquid surface, a tether, at least one pulley, a permanent magnet and a magnetic field angle sensor, wherein two ends of the tether are tied to the float, and are wound on the top end pulley and the optional bottom end pulley, the permanent magnet is installed on one side of the top end pulley and rotates together with the top end pulley under the effect of a friction torque produced by the tether. The magnetic field angle sensor detects a magnetic field produced by the permanent magnet and converts a rotation angle of the magnetic field into a voltage signal, then according to a relationship between the rotation angle of the permanent magnet and a floating distance of the float, a liquid level height is calculated via the output voltage signal. A gear can also be used to calibrate the operating range and accuracy of the liquid level sensor. The liquid level sensor has the advantages of simple design, wide measurement range, easiness in sealing and the like.