Abstract: Urban landscape lake is an important part of ecological city construction． It always has slow flow，weak hydrodynamic exchange and poor self-purification ability． The water quality is susceptible to urban discharge，runoff or human activities． In this article，a three-dimensional model was used to analyze the hydrodynamic characteristics of a typical urban landscape lake—Tianyinhu Lake based on EFDC( environment fluid dynamic code) ． The model was applied from Sep 2011 to Dec 2013 to simulate the changes and spatial-temporal distribution of water age． The paper also analysed the influence of rainfall runoff and wind force to water age． The results indicated that the main force of hydrodynamic in Tianyinhu Lake was the rainfall runoff and the wind driven force was faint． This research conclusion could help to understand the hydrodynamic characteristics of urban landscape water body and the influence of hydrodynamic for water quality analysis． It also provide a certain support for the construction and protection of urban water environment