Abstract: Efficient water and fertilizer management is key to achieving crop yield improvement. Based on the influence of different water and fertilizer management models on the material accumulation, nitrogen absorption characteristics and yield of maize in southwest China, this study aimed to clarify the cultivation mechanism of drip irrigation water and fertilizer integration technology to improve maize yield in southwest China. During 2023 and 2024, a field experiment was carried out in Mianyang, Sichuan using the hybrid of Zhongdan 901 with traditional water and fertilizer management (FM) as the control and water and fertilizer integration by drip irrigation (HM) as the treatment under two planting densities of 60, 000 plants·hm^-2 (D1) and 90, 000 plants·hm^-2 (D2). The results showed that the yield of HM treatment was significantly increased by 22.54% and 32.21% (P<0.05) compared with FM, and the dry matter production at maturity was significantly increased by 32.64% and 15.58% (P<0.05), respectively, under D1 and D2 densities. Compared with FM, the maximum dry matter accumulation rate (T_max) and dry matter accumulation active period (P) of HM treatment were shortened by 1.12d and 3.67 d on average. The leaf area index (LAI) at silking stage increased by 16.52% and 17.89% under D1 and D2 densities, respectively, and the leaf area duration (LAD) after flowering increased by 22.76% and 27.23%, respectively (P<0.05). From the perspective of nitrogen utilization, the proportion of post-flowering nitrogen accumulation under HM treatment accounted for 32.61% (D1) and 29.90% (D2) of the total accumulation. Compared with FM, HM treatment increased leaf nitrogen transport efficiency (NTE) and nitrogen transport contribution to grain (NTCP) by an average of 22.23% and 19.62%, respectively. The net nitrogen assimilation rate (NAR) from silking to maturity (R1-R6) was increased by15.16% (D2), with no significant difference at D1 density. HM treatment significantly increased nitrogen fertilizer partial factor productivity (PFP), nitrogen uptake efficiency (NupE), and harvest index (NHI) by 34.05%, 29.54%, and 12.88%, respectively, compared with FM (P < 0.05) under D1 density. HM significantly increased PFP and NupE by 31.10% and 41.42%, respectively (P < 0.05) under D2 density. Principal component analysis showed that HM treatment was positively distributed along PC1 and PC2, indicating a synergistic improvement in nitrogen fertilizer partial factor productivity (PFP), nitrogen uptake (NupE), and redistribution efficiency (NTE and NTCP), whereas FM treatment was mainly concentrated on the negative side of PC1, reflecting nitrogen utilization characteristics that rely on soil fertility and conventional conservative allocation. Overall, under high-density conditions, drip irrigation combined with water and fertilizer integration significantly enhanced dry matter accumulation rate and total dry matter production by optimizing post-flowering nitrogen uptake and sustaining leaf function in summer maize, ultimately achieving a coordinated increase in yield and nitrogen utilization. This finding provided an effective technical approach for high-yield, high-efficiency cultivation of summer maize in the southwestern region.