Sediment transport is an important issue of the Huaihe River. To study the evolution of the riverbed, the relationship between river flow and sediment transport has been done in the paper, based on long-term measured data in the middle reach of the Huaihe River. Both models developed by Han (2012) and Zhang (2000) were used for assessing sediment transport and channel evolution. Field data collected in four gaging stations, namely, Wangjiaba, Lutaizi, Wujiadu, and Xiaoliuxiang were used. In total, 80 sets of data including runoff, water temperature, cross section, sediment and suspended sediment data were chosen. The relationship was developed to indicate the relationship between sediment transport and sediment factor. The relationship between slope and discharge has been developed based on data measured from 1990 to 2007 in Lutaizi and Xiashankou stations. Results indicate that the roughness coefficient decreases with discharge before floodplain got flooded. After floodplain got flooded, roughness coefficient increases with discharge. On the basis of the relationship among gradient and discharge, channel roughness and other hydraulic factors at the Lutaizi Station on the Huaihe River, the models have been validated. The formula for determining sediment-transport capacity which describes the relationship between water flow and sediment transport at the Lutaizi Station has been developed in this paper. By introducing the Han’s model into Zhang’s formula, the water percentage was included into the sediment transport capacity equation. One suspended sediment transport equation for both coarse and fine sand was developed. By using the data from the Lutaizi Station as the example, the empirical formula for determining transport capacity under equilibrium, erosion and deposition conditions were derived. The annual sediment transport capacity was predicted and validated by using the measured data from 1990 to 2007. Results show that the measured annual sediment transport capacity is 4552 × 10⁴ tons while the calculated annual sediment transport is 4337 × 10⁴ tons, with a difference of 4.7%. From the calculation, it can be concluded that the empirical equation developed for determining sediment transport capacity can reasonably predict the sediment transport in the middle reach of the Huaihe River under different flow conditions.