Large-aperture liquid crystal polarization gratings (LCPGs) hold broad potential applications in beam steering modules due to their advantages of high efficiency and inertia-free operation. However, limited by the aperture of optical components in polarization holographic interference exposure systems, it is challenging to fabricate LCPGs with apertures exceeding 2 in (1 in=2.54 cm) through single exposure. This paper proposes a proximity stepper holographic interference splicing exposure method. By employing a photomask placed in close proximity to the exposure substrate, precise control of single-exposure area positioning is achieved combined with a high-precision displacement stage. Stepper splicing exposure of a 150 mm aperture LCPG is realized. The fabricated grating exhibits a splicing seam of only 26.4 μm and achieves a diffraction efficiency of 96.86%. This paper provides a new idea for the efficient deflection of large-aperture beams.