To quantify the multi-objective synergy/coercion relationship of unified water-sand dispatching in the upper Yellow River, a multi-objective synergy/coercion regulation model based on the Longyangxia-Liujiaxia cascade reservoirs was constructed, and the runoff sequence from July 1996 to June 2022 was regulated. The results indicate that the multi-year average of multi-objective coercion degree in long-term scheduling is 0.36, and it is generally in a state of primary coordination. Affected by the regulation and storage of the reservoir group, the multi-objective synergy/coercion relationship in typical years of high, normal, and low water is basically consistent throughout the year. During the flood season, it is in the primary coordination stage, while during the ice-flood prevention period, it changes from barely coordination to being on the brink of coercion. During the non-flood season, it returns from barely coordination to primary coordination. In the early stage of the continuous dry year group, due to the large amount of water replenishment in the cascade reservoirs and timely water storage during the flood season, the multi-objective synergy/coercion relationship is basically the same as that of typical years. However, in the later stage, due to the extremely dry incoming water and low water level in the reservoir, the degree of multi-objective coercion increases significantly, and reaches severe coercion in the ice-flood prevention period.