In the process of increasingly deepening aging population in China, the selection of the elderly living modes and the elderly welfare are becoming more and more important. Does tradition living mode together with sons and daughters in China improve the elderly welfare really? Based on the unique intergeneration relationship of two-way feedback, this paper takes the elderly dietary quality as an example, and discusses the effect of living together with sons and daughters on the elderly welfare from the perspectives of parental demand and offspring demand. And it conducts an empirical test by using the data of China Health and Nutrition Survey in 2009 and 2011. It comes to the following conclusions:firstly, living together with sons and daughters reduces the balanced dietary scores of the elderly instead of improving the elderly welfare, especially in terms of the younger, rural, and female elderly; secondly, as for effect channels, the elderly living together with sons and daughters selflessly devote themselves to the child care, but their own care demands are not satisfied better; the downward shift of the core of intergeneration relations accounts for the reduction in the elderly dietary quality. This paper provides empirical evidence for the formulation of intervention policy on the elderly welfare with different living forms and the construction of social pension service system.