A liquid level sensor system is disclosed for remotely monitoring the liquid level in a tank. The system comprises a first fixed portion with a first liquid level response unit, and a second fixed portion with a second liquid level response unit. A guide tube is inserted into the tank and attached to the bottom of the first fixed portion. The guide tube is provided with a multitude of ports, such that the liquid level in the guide tube is flush with the liquid level in the tank. The first liquid level response unit comprises a float floating up and down with the variation of the liquid level in the guide tube, a rotating shaft rotating around a relatively fixed axis of rotation in the up and down floating process of the float, and a permanent magnet. The second fixed portion is attached to the top of the first fixed portion. The second liquid level response unit comprises a PCB, a magnetoresistive angle sensor chip, and a control circuit electrically connected to the magnetoresistive angle sensor chip. The magnetoresistive angle sensor chip outputs an analog voltage signal to the control circuit according to the rotation angle of the permanent magnet, and the control circuit calculates the height of the liquid level according to the analog voltage signal.