Abstract:Due to the impact of upstream reservoir, control project and climate change, the Yellow River Inner Mongolia reach has the characteristics of different sources of runoff and sediment, less water and more sediment. This phenomenon leads to sediment deposits, sharply decline and morphological evolution violently. This is seriously threatening the safety and ecological environment during summer flood and ice flood period. Shizuishan and Toudaoguai hydrologic station runoff and sediment transport process were chosen to analysis water-sediment time-order character, motion state and evolution characteristics by using spectral analysis method, R/S range analysis method and Markov method from 2009 to 2016. The results showed that the sediment transport variation period was one year at Shizuishan and Toudaoguai hydrologic station, but runoff variation period was one year and six months for the two stations respectively. Runoff Hurst number was 0.576 and 0.515, and sediment transport Hurst number was 0.519 and 0.249 respectively at Shizuishan and Toudaoguai hydrologic station. The probability of abundant flow low sediment and less discharge high sand was about 50%, the sum of the limit probability of large discharge high sediment and water shortage low sediment transport was greater than 0.8. There were asynchronization and incongruity of runoff and sediment time-order characters by the effect of incoming runoff and sediment process, hydroclimatic characteristics, human activities. Runoff and sediment transport process will be gradually coordinated in the future.