Context and objective: Optimizing row spacing to improve canopy structure and regulate source-sink relationships under water-limited conditions is a promising strategy for achieving both water conservation and yield stability in drip-irrigated winter wheat in arid regions. However, the intrinsic mechanisms-particularly those related to source-sink regulation-by which wide-narrow row planting interacts with deficit irrigation remain poorly understood. This study aimed to elucidate how wide-narrow row configurations regulate population structure, source-sink balance, and yield formation of drip-irrigated winter wheat under different irrigation regimes. Methods: Field experiments were conducted in 2024 and 2025 using a two-factor design. Two planting patterns were evaluated: uniform row spacing (M0) and wide-narrow row spacing (M1), combined with three drip irrigation levels: conventional irrigation (CK, 4500 m3 & sdot;hm- 2), 20% reduced irrigation (D1, 3600 m3 & sdot;hm- 2), and 40% reduced irrigation (D2, 2700 m3 & sdot;hm- 2). Canopy transmittance (CT), leaf area index (LAI), SPAD, net photosynthetic rate (Pn), dry matter accumulation, and grain filling were measured, and dynamic source-sink relationships were analyzed. Results: M1 treatment significantly improved the canopy light environment of drip-irrigated winter wheat. At the anthesis, bottom-layer CT under M1 increased by 6.5-7.0-fold compared with M0. During grain filling, CT of the flag leaf layer under M1 remained stable, whereas a declining trend was observed under M0. Under water stress, LAI in the M1 treatment decreased by only 5-8% during the early and middle grain filling stages, markedly lower than the 21-49% reduction observed under M0. The Pn of M1 increased by 13%, effectively enhancing the stability of dry matter accumulation. Over two years of experiments, grain yield under M1 was 5-8% higher than that under M0 in CK and D1 treatments. Notably, the M1D1 treatment achieved an average yield of 9410 kg & sdot;hm- 2, exceeding that of M0CK by 2%. Partial least squares path modeling (PLS-PM) analysis demonstrated that planting pattern optimized the source-sink balance primarily by positively regulating canopy structure and photosynthetic traits. Conclusions: Wide-narrow row planting under deficit irrigation synergistically enhanced source photosynthetic efficiency and sink filling canopy by optimizing the canopy light environment. A combination of wide-narrow row planting with 3600 m3 & sdot;hm- 2 irrigation maintained high wheat yield while saving 20% of irrigation water, whereas uniform row planting required conventional irrigation to achieve comparable yields. Implications: These findings provide a scientific basis for optimizing the row spacing configurations in dripirrigated winter wheat to achieve water conservation and yield stability in arid regions, contributing to regional food security and advancing the sustainable development of water-efficient agriculture.