In a case study of Xifeng City on the Longdong Loess Plateau,climate change trends and its effects on soil moisture,as well as the evolution of soil moisture were analyzed based on the 50-year climate data and the 20-year observation data of soil moisture.Results show that temperature increased and rainfall decreased in the recent 50years.From 1991to 2010,soil moisture in Longdong presented a downward trend on the whole.In spring,soil moisture decreased more severely and in summer,soil moisture had a similar trend,but the rate of change was significantly lower than that in spring.In fall,soil moisture in shallow soil layer showed a downward trend,while the deep soil presented a rise trend.For topsoil,soil moisture in each season was negatively correlated with temperature and positively correlated with precipitation.For deeper soil layer,the correlations of soil moisture with temperature and precipitation depended on season.The effects of potential evapotranspiration on soil moisture were characterized by an antiphase monthly and annually,and the basic trends were synchronized.The analyses of soil moisture evolution and its influence factors may provide some references to the decision making for understanding soil moisture evolution,rationally using climatic resources,adjusting agricultural and ecological patterns and positively coping with climate change