Fiber optic liquidlevel sensor has many excellent properties, such as electric isolation, resistance to electromagnetic interference, anticorrosion etc. And it provides safe operation in inflammable and explosive environment. Fiber optic sensors measure the liquid level generally based on different transmission characteristics of optical signals in different media. It comprises continuous liquid level sensors and point liquid level sensors. Fiber optic pointlevel sensors can indicates the liquid level and give an alarm at certain levels. This paper introduces four kinds of fiber optic pointlevel sensors based on different principles, including total internal reflection, Fresnel reflection, scattered light, and bending loss of the optic fiber. The structure, principles, advantages and disadvantages, and important performances, such as precision of each sensor are described in detail and their development status and trends are given finally.