The SHRIMP UPb ages for zircons in welded tuff from Wangchang Formation in Dongchuang Area，Yunan Province, are reported in this paper，and the 207Pb/206Pb age of the point of intersection between discordant and concordia curves for zircons with automorphic and zonal tecture in P13 are 2317±13 Ma(n=13，MSWD=3.3)，and weighted average age is 2299±14 Ma(n=13，MSWD=5.9)，implying that the sedimentary age of Wangchang Formation is early to midpaleoproterozoic. The sedimentary age of underlying four formations in Dongchuang Area almost are ten billion years older than the Kunyang Group in central Yunnan and the Huili Group in south Sichuan Province. To distinguish the underlying four formation(Sahaigou，Wangchang，Caiyuanwang and Pingdingshan Formations) from the Kunyang and the Huili Group，and the independent the Tangdan Group which is one of the oldest gourp in Kangdian Area so far is advised to be established. The Tangdan Group experienced convergence process(Dongchuan Movement) during early Paleoproterozoic and divergence process during late Paleoproterzoic，and may be a small independent block that constitute part of Columbia Supercontinent to ancient Yangtze Nucleus.