In order to analyze the origin of water and sediment in the Yellow River and predict the future water and sediment situation, two typical watersheds (Xinshui River and Zhujiachuan watershed) in the middle reaches of the Yellow River were selected as the study area. Based on the measured data of water and sediment from 1956 to 2018 at the hydrological station and rainfall station, the Mann-Kendall trend, the change-point analysis, the cumulative anomaly method and the Morlet wavelet method were used to analyze the variation trend of water and sediment in typical watersheds. Furthermore, the attribution of water and sediment changes were analyzed by using the double mass curve method, and the relative contributions of climate change and human activities to water and sediment change were quantified. The results showed that from 1956 to 2018, the average annual runoff in the Xinshui River and Zhujiachuan watershed was 11.9×10⁷ and 1.7×10⁷ m³, respectively, and the average annual sediment discharge was 12.3×10⁶ and 9.8×10⁶ t, respectively. The runoff and sediment discharge showed a significant decreasing trend. The abrupt change year of runoff in the Xinshui River and Zhujiachuan watershed was 1980 and 1984, respectively, and the abrupt change year of sediment discharge was 1980 and 1972, respectively. The changes of water and sediment in the watersheds had obvious periodicity, and the first main cycle of runoff change was 45 years and 16 years, and the first main cycle of sediment transport change was 9 years and 15 years, respectively. The contribution rate of rainfall to the reduction of runoff in Xinshui River and Zhujiachuan watershed was 19% and 8%, respectively, and the contribution rate of rainfall to the reduction of sediment discharge was 25% and 35%, respectively. The Contvibution rate of rainfall is far lower than that of human activities, which are the leading factor of the sharp decrease of runoff and sediment discharge. The research results can provide scientific suggestions for water and sediment control of the Yellow River.