In this paper，the basic situation of underprivileged children were analyzed in Shanghai by the underprivileged children living conditions survey results which were conducted by the Shanghai Municipal Bureau of civil affairs in the whole city in 2015. The current situation and existing problems of the underprivileged children discovery mechanism was summarized and the discovery and reporting system of the underprivileged children in United States and Australia was introduced. Some policy suggestions have been put forward that building the discovery and protection system of underprivileged children，establishing a network of the underprivileged children discovery mechanism and organizing and directing social forces to participate in the underprivileged children discovery mechanism and so on.