Based on the conceptual model of growth drag and some relevant researches,a growth drag model to water and land resources in the development of urbanization is introduced.By taking Xi'an City as an example,the decline of levels due to restrictions of land and water resources is calculated and analyzed using the revised growth drag model and econometric theory.Results show that because of the constraints of water resources,urbanization rate may decline by 0.010875% annually.Because of the constraints of land resources,urbanization rate may decline by 0.004696% annually.Total growth drag is about 0.015571% and the role of water resources is greater.This is mainly due to the growth of land resources in Xi'an City,the intensive use of land and water resources,and a decline in capital elasticity.In view of the trend of change about the use of resources over time,however,the damping data fo Xi'an City may become greater in the future.