在拍摄低频全息光栅的现有研究中，仅对干涉条纹的宽度和对比度进行深入分析，讨论杨氏双缝干涉条纹在屏上沿Y轴或X轴上的分布状况，并没有研究干涉条纹方向的斜率变化。选择马赫曾德尔干涉光路，在若干次拍摄低频全息光栅实验中找到了干涉条纹方向斜率k1与两干涉点光源连线斜率k2的变化规律，并用相干光理论和数学函数推导了两者间相互制约的内在变化关系，即k1×k2=-1。研究结果为拍摄不同条纹方向斜率的低频全息光栅提供了理论依据和实验基础，扩大了低频全息光栅在精密测量中的应用领域。

In previous studies on recording the low-frequency holographic grating via the Mach-Zehnder interferometer, a detailed analysis of the width and contrast of the interference fringes has revealed their rules of variation. This paper focuses on the fringe orientations for recording by the Mach-Zehnder experiment. It is confirmed experimentally and theoretically that the direction slope of the interference fringe orientations k1 is dependent on that of the connection line of the point light source k2 of two interference light, with a relation of k1×k2=-1. This result provides a theoretical and experimental basis for recording the different fringe-orientation low-frequency holographic grating and their applications in precision measurements.