The report，based on the migrant population dynamic monitoring data of National Health and Family Commission of P.R.C in 2015，analyzes the characteristics of floating elderly people’s flow and lives in megacities. In terms of flow characteristics：there are differences in the source of floating elderly people’s household registration，floating elderly in Beijing and Shanghai are mainly non-agricultural residents，while floating elderly in Guangzhou and Shenzhen are mainly agricultural household residents；Floating elderly have the choice tendency on “nearby” inflow areas，Inter-province mobilization in nearby provinces appears in Beijing and Shanghai，while Intra-province mobilization is the bigger part in Guangzhou；There are differences in the time that floating elderly lived in megacities，compared to Guangzhou and Shenzhen，migrating time in Beijing and Shanghai are longer. Taking care of the younger generation，pension and seeking jobs or doing business are main flow reasons，floating elderly who choose “pension” are mostly have non-agricultural household registration，and those who choose “seeking jobs or doing business” are mostly have agricultural household registration；In terms of living characteristics：the retirement pay of retirees is the main source of economic support for floating elderly，followed by family support and labor income；There are differences in floating elderly people’s income and discrepancy between different megacities. Families in Guangzhou with floating elderly have the lowest income on average，and those in Beijing have the highest housing expenditure；Most of floating elderly are in good health，which are related to education and family income，and most floating elderly have health insurance；The majority of floating elderly have friends in Megacities，and the more healthy floating elderly are，the easier they have more friends.