对由FBG (布拉格光纤光栅)和LPFG (长周期光纤光栅)构成的SFG (超结构光纤光栅)，采用耦合模方程的相似变换解法，研究了应变梯度和温度梯度对SFG的透射谱和反射谱的影响。模拟结果表明，SFG在应变梯度或温度梯度的作用下，其反射光谱和ν阶包层模的透射光谱按确定规则独立漂移，据此可以同时求出光栅所在位置的应变和应变梯度，或温度和温度梯度。

For the Superstructure Fiber Grating (SFG) consisting of a Fiber Bragg Grating (FBG) and a Long Period Fiber Grating (LPFG), a similarity transformation method for the coupled mode equations is presented, and the effects of strain and temperature gradients on the transmission and reflection spectra of SFG are investigated. The simulation results show that by the effects of strain or temperature gradient, its reflection spectrum and transmission spectrum corresponding to ν order cladding mode shift independently according to an established rule. On this ground, it is possible to simultaneously calculate the strain and its gradient, or temperature and its gradient at the location of SFG.