Urban poverty is a new phenomenon sprung up in the mid of 1990s’ and spread as the time going.Defining the Lowest Security Line Standard is an important aspect of urban poverty assistance job.Inspired by the International Poverty Line Standard,this thesis attempts to introduce some new methods that seem more simple and convenient.With these methods,we could calculate a certain city’s Lowest Security Line Standard using some “picking up” data,which could be easily found in yearbooks .In this essay,we introduce two kinds of concrete defining methods:(1)single index methods,including total index,average index and percentage;(2)complex indexes methods,also including total index and average index.We testify the two methods by comparing the calculating standard with the actual standard of the Lowest Poverty Line of the twelve cities in Jiangsu Province and conclude that these methods are valid.