[Objective] Current research on water-sediment characteristics of the Huaihe River mainstream mainly focuses on single channels, while studies on water-sediment characteristics, relationships, and diversion patterns in its bifurcated channels are limited. This study selects the typical bifurcated section from Wangjiaba to Nanzhaoji (hereinafter referred to as “Mengwa section”) in the middle reaches of the Huaihe River, aiming to clarify the variations in water-sediment characteristics and diversion patterns of typical bifurcated channels. [Methods] A combination of cumulative anomaly analysis, Mann-Kendall (M-K) trend test, R/S analysis, and Morlet wavelet analysis was used to study the water-sediment inflow characteristics of the bifurcated channels in the Mengwa section from 1985 to 2020. The driving factors of abrupt changes and variation trends in water and sediment conditions were explored. The water-sediment coordination relationships and sediment transport capacity variations were evaluated using water-sediment relationship curves, and quantitative ratios of flow and sediment diversion across bifurcated channels of the Mengwa section were provided. [Results] The annual runoff at Wangjiaba station (total) showed no significant increasing or decreasing trend, while the sediment concentration displayed a pronounced decreasing trend, stabilizing below 0.15 kg/m³ after 2010 and continuing to decrease in the future. An abrupt change occurred around 1995. Sediment retention by reservoirs, agricultural land use changes altering underlying surfaces, and soil and water conservation measures were the primary driving factors of sediment concentration reduction. The sediment coefficient showed a decreasing trend, with external influence coefficient “a” gradually decreasing and sediment transport fitting coefficient “b” gradually increasing. This indicated a continuous reduction in sediment inflow intensity and an enhancement of the channel’s sediment transport capacity, promoting channel scouring. Meanwhile, the main channel cross-section exhibited sustained expansion, indicating an ongoing erosional state in this river section. The flow diversion ratio of the Menghe River was generally positively correlated with total flow in this section. At 2 000 m³/s (low-to-medium flow level), the main channel on the Huaihe River’s southern branch served as the primary flow passage. As the flow increased, the weight diverted through the Meng River progressively rose. Below the flow level of 6 000m³/s, its diversion capacity slightly declined, while at 6 000m³/s, the flow achieved equitable flow diversion with the mainstream of the Huaihe River. The sediment concentration ratios of each bifurcated channel were approximately equal to the ratios of their respective flow sediment transport capacity. [Conclusion] These findings provide theoretical support for sediment concentration calculation models in bifurcated channels during numerical simulations of water and sediment dynamics in the middle reaches of the Huaihe River, while offering a scientific basis for adopting long-distance dredging schemes in the river’s channel regulation strategies.