Abstract: The follow-up power is still lacking for the water and sediment regulation in the Xiaolangdi Reservoir. The follow-up power of flow is required for the reservoir to discharge the sediment and the lower river channel, finally to transport the sediment into the sea, as the large flow of water is released during the water regulation stage with the reduction of large flow into the reservoir. It is necessary to fully explore the potential of the Sanmenxia Reservoir, providing the follow-up power for water and sediment regulation in the Xiaolangdi Reservoir. In this study, the possible boundary conditions were analyzed with the formation of a double sediment erosion base level via rebuilding the bottom hole of the Sanmenxia reservoir. The restricted operation water level of 305-312 m was also set in several flood seasons, according to the early flood season during July to August, and the later flood season during September to October. Several operation water levels of 318-326 m were set in the non-flood season, and nine schemes were combined with different water levels in flood season and non-flood season, considering the scouring and silting characteristics of the Sanmenxia Reservoir area. A mathematical model was constructed for the sediment erosion and siltation in the Sanmenxia Reservoir. The measured data from July 1, 1973, to June 30, 2019, were utilized to calibrate the parameters of the model. The calculation error of reservoir siltation was controlled within 5%. After that, the schemes were calculated using the verified mathematical model. The boundary conditions were that: in the Xiaolangdi Reservoir area in April 2020, the future inflow of 27.205 billion m³ and the incoming sediment of 800 million tons of reservoir, from the accumulated erosion and siltation in the reservoir area, the accumulated increase in the elevation value of Tongguan (erosion base level of the lower Weihe River), the accumulated power generation of the power station, the average annual discharge over 2 600 m3/s in the reservoir, the largest wetland area in the reservoir area and the change of inundated population in the reservoir area. Nine schemes were evaluated using the fuzzy optimization model, and then the optimal water level scheme of the Sanmenxia Reservoir was proposed under the condition of reducing the erosion base level. The optimal water level was 308 m in the early flood period during July to August, 312 m in the later flood period during September to October, and the highest water level was 321 m in the non-flood period. The optimal scheme presented an increase of 42% in the discharge above 2 600 m3/s, a cumulative increase of 9% in power generation capacity, and a 73% increase in the wetland area. The possible impact was analyzed for the rising of water level, particularly on the elevation of Tongguan, the risk increase of eroding bank in the reservoir area, where the observation during specific implementation in time and formulating risk response plans. The findings can provide a promising application to enhance the follow-up power of water and sediment regulation in the Xiaolangdi Reservoir, thereby improving the comprehensive benefits of the Sanmenxia Reservoir.