Xinjiang is located in an inland arid area, and it faces significant challenges in water resource supply and demand, with a fragile ecological environment. Exploring the internal relationship between the time–space distribution of agricultural water–soil matching and the evolution of the ecosystem service value (ESV) in the Tailan River Irrigation District of Xinjiang from 2000 to 2020, this study provides theoretical guidance for the balance of agricultural water–soil resources and the healthy and sustainable development of the ecological environment in the irrigation district. By integrating the water–soil matching coefficient and the equivalent factor method, the spatiotemporal distribution of agricultural water–soil matching and the spatiotemporal evolution of the ESV under the change of land use (LU) in the irrigation district are analyzed. Based on the Pearson correlation, the trade-off synergy between the two is explored. The results show that the following occurred in the past 20 years: (1) Grassland and dryland are the two categories of land with the biggest transfer-out and transfer-in areas in the Tailan River Irrigation District, and the conversion areas are mostly in Jiamu Town and Guleawati Township. (2) The area and reclamation rate of the irrigation district increased gradually, among which the highest reclamation rate was 85.93% in Kezile Town and the lowest was 76.37% in Guleawati Township. The average Gini coefficient of agricultural water–soil in the irrigation district is 0.118, which is absolutely fair. (3) Kezile Town has the highest agricultural water consumption, but the matching of agricultural water–soil always fluctuates between the best and the worst. The agricultural water consumption in Communist Youth League Town is the lowest, but the matching of agricultural water–soil has remained the best for many years. (4) The ESV of the irrigation district showed an overall increasing trend, from CNY 243 million in 2000 to CNY 678 million in 2020; in addition, soil conservation, hydrological regulation, grassland, and dryland contributed the most to ESV in each period. (5) There was a significant trade-off relationship between agricultural water–soil matching and ecosystem services in the Tailan River Irrigation District, while there was a significant synergistic relationship between ecosystem services.

Aiming at the problems of a fragile ecological environment, water shortage and system uncertainty in inland arid irrigation districts in Xinjiang, this study takes sustainable development as the guide, selects the Tailan River Irrigation District in Xinjiang as an example, and constructs a multi-objective optimal allocation model of agricultural water and soil resources in irrigation districts driven by water–carbon–economy synergy. The model aims to minimise irrigation water shortage, maximise crop carbon absorption and maximise economic benefits. By comparing six multi-objective algorithms such as APSEA, CMEGL, DCNSGA-III, DRLOS-EMCMO, MOEA/D-CMT and θ-DEA-CPBI, the optimal is selected based on the hypervolume (HV) index. The surface water, groundwater and crop-planting structure of five decision-making units in the irrigation district from 2021 to 2024 were optimised. Further, combined with the entropy weight–TOPSIS coupling-coordination comprehensive-evaluation model, the scheme evaluation system is constructed to screen the optimal configuration scheme of each year and unit. The results show that the MOEA/D-CMT algorithm has the highest HV value in each unit model over the years, which is the best solution algorithm for the model in this paper. The comprehensive evaluation value and coupling coordination degree of the optimal scheme of each unit fluctuate between years, and the difference between units is significant. Compared with the original planting and water source allocation scheme of the irrigation district from 2021 to 2024, the overall planting area of the optimised irrigation district is moderately reduced, forming an optimised pattern of ‘cotton pressure, grain expansion, economic increase and strong forest’; after optimization, the overall water shortage in the irrigation district is reduced by 1.4~11 million m³; the total amount of crop carbon absorption increased by 90.3~128.8 million kg; the net economic benefits increased by CNY 21.5~68.2 million. The research can provide decision support for the optimisation of the water and soil resource system in arid irrigation districts and has a scientific reference value for promoting the sustainable development and modernisation of agriculture in the inland irrigation districts of Northwest China.