Based on survey data of China’s health and nutrition between 1989 and 2009,this paper studies the transformation of household poverty and non- poverty state as well as the impact of durability on such transformation with the help of survival analysis. The result shows that household’s getting into poverty and emerging from poverty coexist in an asymmetric proportion,the influence of time span of continued poverty and continued non- poverty on transformation of poverty state shows different changing trend because of the different choice of absolute poverty line and relative poverty line. In addition,as for the change of poverty,poor households possess the flow- up possibility from the perspective of absolute poverty. However,from the perspective of relative poverty,poverty demonstrates continuous quality. Consequently,solidified tendency of social class is revealed in this paper.