基于简化的光纤三层模型，从折射率传感和长周期光纤光栅级联特性两方面对应用长周期光纤光栅作液位传感器进行了研究，当以峰值损耗为传感参量进行测量时，在没有发生过耦合的情况下，在一个较宽的范围内，光栅峰值损耗与进入液体的百分比成很好的线性关系；而当有过耦合发生时，光栅峰值损耗与进入液体的百分比不再一一对应.

On the basis of simplified three-layer model, and in two aspects such as refractive index sensing and step-index fiber grating property, the study on using long-period fiber grating as liquid level sensor in theory was made. When the resonance peak loss as a sensing parameter is measured, the overcoupling did not happen, within a wider range, the linear relationship of the resonance peak loss and the percent of the LPG immersed in liquid would become very well. In contrast, the grating peak loss did not correspond with the percent of immersed liquid as soon as the overcoupling happened.