Abstract: The grid governance of a community is an institutional design based on the conventional problems of cities in China. It is of great significance for upgrading grassroots governance level and promoting social harmony and stability. Yet in case of a public emergency， anew phenomenon of fragmentation has appeared in communities under grid governance. To cope with a public health emergency，Jdistrict adopted the point-leader responsibility system. It provides a case for studying how a grassroots government addresses the new fragmentation issue to promote its governance quality on the three dimensions of space，right and liability，and information. The point-leader responsibility system is a higher level of the current grid governance model，and the purpose of its establishment is to deal with a public emergency in a better way. Its holistic governance concept and integration mechanism design are recommendable. The grid governance of a community should maintain and expand its open-source feature， while guarding against the unexpected consequence brought about by institutional innovation.

Key words: public emergency；grid governance；governance fragmentation；point-leader responsibility system