To fabricate high-quality holographic gratings and improve the fringe stability of the beam-splitting amplitude exposure system， this study analyzes the effects of different beam-splitting devices on fringe stability and designs a phase-locking system for holographic grating interference fringes.First， based on the principles of interference exposure and the impact of fringe drift on exposure contrast， we analyzed the directional requirements for light sources when using different beam-splitting components. A detection method for interference fringe variations， utilizing Moiré fringes from a reference grating， was investigated. Suitable detectors and actuators were selected， and a closed-loop fringe phase-locking system was designed and implemented using an STM32 microcontroller integrated with a PID algorithm.Experimental results demonstrate that the locking system achieves a control frequency of 1 kHz， effectively suppressing low-frequency drift primarily within 0~3 Hz. After stabilization， the root mean square （RMS） value of fringe drift was reduced to 0.004 7λ. When laser pointing stability is insufficient， the proposed grating-based beam splitting combined with single-point phase locking can meet the fringe stability requirements for large-scale holographic grating fabrication.