///This
paper was based on the field investigation of the typical geological sections
and multiple methods of laboratory tests on the samples from the slopes along
the Baoshan-Tengchong highway and adjacent area in Yunnan Province. It
discovered a swelling clayey diatomite in the Neogene lacustrine strata, named
Mangbang formation, at Tengchong area Yunnan Province. The discovery of the
swelling clayey diatomite in Mangbang Basin, as well as the researches on its
engineering properties, is not only instructive for realization of the
mechanism of related geo-hazards along the Baoshan-Tengchong high way, but also
helpful to understanding the engineering properties of some lacustrine deposits
and their easily causing geohazards in southwestern China.