The 1 : 50,000 regional geological mapping of the Lantian area collected abundent data of Presinian sections, angular unconformity interface between the Xiuning Formation (Sinian) and the underlying strata as well as subsequent tectonic events, confirming that the area belongs to the Neoproterozoic orogen, that there exists the Mesoproterozoic formations with intact sequence on the Lantian area, and that the Sinian - Cambrian strata are a sedimentery cover uncon-formably overlying the Presinian. Then this cover formed a synclinal basin as a relic on the slide - superposition system under the condition of regional stretch mechanism during the Caledonian cycle. The structure action in the Mesozoic period reformed remarkbly only the structural framework of this area. It caused neither orogenies nor the..tectonic window.