The optical fiber liquid-level measurement proposed in this paper is based on the leakage of light transmitted in an optical fiber. Owing to the leakage, when the refractive index of external media changes, the transmission loss will change, and then the liquid-level can be obtained by measuring the change of the intensity of emergent light. First, a brief analysis of the basic operating principle of the optic fiber liquid-level sensor based on light leakage is presented. Second, a classification is provided according to the implementation methods of leakage in the horizontal and vertical directions. Third, some important measurement parameters are compared, such as processing difficulty, measuring range and accuracy. Finally the prospect of its application is made in this paper.