<p>This study aims to assess the impact of conservation tillage on the phosphorus (P) distribution in aggregates with different particle sizes and identify the key aggregate size influencing the availability of soil P. This study was based on a 13-year field experiment arranged in a completely randomized design using a factorial design with two factors: tillage regimes (conventional tillage: CT; no-tillage: NT) and two straw management practices (+ S: straw retention; -S: straw removal). The cropping system is an annual rotation of winter wheat and summer maize. Bulk soil samples were collected, and aggregates were isolated by wet sieving. The P fractions in both bulk soil and aggregates were quantified using the Hedley sequential extraction. For bulk soil, conservation tillage increased total P (TP), Olsen-P, and organic P content. Compared with CT, NT significantly enhanced highly labile P pools, with H₂O-P_i and NaHCO₃-P_i increasing by 30.28% and 46.28%, respectively. Under straw retention, the HCl-P_i content increased significantly by 13.10% as plowing frequency decreased, whereas under straw removal, there was no significant difference in HCl-P_i between NT and CT. For aggregates, straw management had a greater impact on their TP and P fractions than tillage regimes. On average, 50.4% and 60.4% of the TP and highly labile P pools were concentrated in macroaggregates, respectively. Meanwhile, conservation tillage significantly increased the mass proportion of macroaggregates and enhanced aggregate stability. These findings suggest that conservation tillage promotes soil P accumulation, particularly labile P pools, and highlight the crucial role of macroaggregates in this process.</p>