Abstract: This paper discusses the maximum entropy spectrum analysis of runoff time series, compares it with traditional spectrum analysis, and presents the high-resolution character of the maximum entropy spectrum and the prospect of its application in hydrology.The analysis and calculation of the annual runoff time series at Lanzhou station on the upper reaches of the Yellow River, prove that the significant periods of the annual runoff are 11, 6.25 and 3 years at Lanzhou station.The conclusion illustrates the feasibility of this method and provides scientific data for runoff forecasting.

Key words: time series, spectrum analysis, maximum entropy, annual runoff