Seting Yanan City as an example, the soil and water loss during the urbanization in the Loess Plateau area and its negative impact on the urban eco-environment are analyzed. The human activities of urbanization will speed up the soil and water loss leading to endangerments, specially such as the increase of the silts in rives, the lift of the riverbed as sedimentary deposits, the pollution of water, soils and air, and resulted in flood and geology calamities. The aim of the article is to lead us paying more attention, to explore the protective and controlling ways and means of solving the questions, to minimize the soil and water loss due to human activities in urbanization, specially in the Loess Plateau area of dense hills and gullies resulted in serious soil and water loss, in order to provide safeguard and service to the construction of better cities'eco-environment.