A thorough analysis of the characteristics of runoff and sediment changes in Inner Mongolia Reach of Yellow River is the premise and basis for the study of the Yellow River control strategy, runoff and sediment resources allocation and the layout of important water conservancy projects. So, based on the long time series data of runoff and sediment (1955-2014) from 3 major hydrological control stations (Bayangaole, Sanhuhekou and Toudaoguai) in Inner Mongolia Reach of Yellow River, the indexes of inhomogeneity, concentration and change range of runoff and sediment were analyzed and the annual and inter-annual variation characteristics of the runoff and sediment were investigated using Mann-Kendall trend test and wavelet analysis. The results show that the annual variation of runoff and sediment time series was that the inhomogeneity and concentration degree of sediment discharge was greater than that of runoff, the concentration periods of runoff were mainly in August and September, but those of sediment discharge mostly occurred in August at each station. The inter-annual variation of runoff and sediment rime series showed that the amount of runoff and sediment decreased significantly with the characteristics of multi-scale oscillation and periodic change cycle at inter-annual and inter-generational scale.