Abstract: The Yaoba cave with a great value in tourism and scientific research is situated about 5 km to north of Baojing county. The cave was vertically developed in do lomitite and dolom itized limestone and controlled by a fracture zone in the Baojing-Fuxing area. The form ation of the cave is closely related to the special geological tectonic environment. Authors discussed the cave sediments-speleothem in particular and its relativity on the base of cave formation characteristics. The cave has all types of cave sediments including debris sediments and sub-chemical deposits and formed upper, middle and lower three different depositp latforms. These platforms and its accompanying deposits display characteristics of cave shape, deposits and its sediment processes. The study has completed the origin classification for sub-chemical deposits and suggests that the wall flow stones, stalactite, stalagmites and stalacto-stalagmites accumulated together could form scenery spotswith great importance in tourism. The No.1 stalagmite with perfect depositcycle, texture and structure characteristics indicates that the deposit of the glacial stage during 30～10ka BP. On the basis of synthetic study about the cave and its sediments, and combined with the Tertiary and Cretaceous sediments and the relationship between the accom panying deposits, it is concluded that the Yaoba cave was formed during the Cretaceous period.