Due to severe water shortage, reclaimed water irrigation is the primary method for agricultural production in western China, while its contribution to soil microplastics (MPs) pollution remains unclear. This study investigated the distribution and risks of MPs in wastewater treatment plant (WWTP), reclaimed water and irrigated soils, and elucidated their relationships. The results showed that, despite the removal efficiency of 87.5 %, many small-sized MPs remained in the reclaimed water. Irrigation of reclaimed water leads to the extensive accumulation of MPs in soils, mainly as 0.05-0.1 mm of polypropylene and polyamide fragments and fibers. Redundancy analysis (RDA) revealed that reclaimed water is the primary source of MPs in the saline-alkali soils, followed by domestic waste and residual agricultural mulch. Risk assessment results showed that the overall pollution load index (PLI) of reclaimed-water soils, domestic-waste soils and farmland soils was 1.74-1.82, and the species sensitivity distribution (SSD) indices were 0, which indicated a generally low ecological risk of MPs in the study area despite their pollution. These findings provided a deep understanding of the interrelationship between reclaimed water reuse and soil MP pollution, which highlights the environmental trade-offs of water reuse practices in arid zones.