In recent decades, the Poyang Lake area has experienced a rapid road expansion, which has brought serious threats to the local ecology and environment. Road expansion leads to wetland landscape fragmentation, habitat connectivity and habitat quality decline, which poses a serious challenge to wetland protection and sustainable development of Poyang Lake. Quantitatively assessing the impact of road expansion on landscape patterns and habitat quality is crucial for road planning and ecological protection. Taking the Poyang Lake area as an example, this study uses road data and land use/cover change data to analyze the spatiotemporal changes in landscape fragmentation from 2000 to 2020 using the effective mesh size (m_eff). The InVEST model is employed to analyze the impacts of road expansion on habitat quality. The results indicate that: (1) Over the past 20 years, the process of road expansion in the Poyang Lake area has accelerated, with road mileage increasing from 5152.69 km to 9213.18 km, an increase of 4060.49 km, approximately 0.79 times, among different kinds of roads, railways and highways had obvious increase of mileage, with an increase of 1482.25 km and 952.95 km respectively. Road expansion has intensified regional habitat fragmentation, with m_eff decreasing from 3754.32 km² in 2000 to 2026.49 km² in 2020, a reduction of 46.02%; (2) From 2000 to 2020, the area of natural habitats occupied by road expansion increased from 84.16 km² to 111.92 km², an increase of 27.76 km², accounting for 0.06% of the total natural habitat area, with forest land being the primary type of occupied natural habitat; (3) Road expansion has led to an accelerated decline in regional habitat quality, with habitat quality dropping from 0.74 to 0.71 from 2000 to 2020, a decrease of 4.6%. Habitat quality is affected by both direct and indirect impacts of road expansion. The total impact on habitat quality caused by road expansion in Poyang Lake area from 2000 to 2020 was 9.63%, of which the direct impact of road expansion was 2.65% and the indirect impact of road expansion was 6.98%. Railways, highways, and national roads have a greater indirect impact on habitat quality than direct impact, while provincial roads have a greater direct impact than indirect impact. Therefore, it is necessary to control road expansion in the Poyang Lake area, focus on the direct occupation and indirect impact of the road expansion process on natural habitats, and take effective measures to coordinate road construction with the protection of natural habitats and biodiversity to promote regional sustainable development.