This paper discusses the stratigraphical problems concerning the Jiabula Formation and the longzi Lower Jurassic in Southern Xizang, China.1.The Jiabula Formation in the Jiangze area is redefined. Study of the am-monoids and foraminiferals it contains shows it to be of early Cretaceous to late Cretaceous (Turonian) in age. In the southern area of the Jolmo Lungma region, the Kangpa Group can be regarded as the equivalent strata.2.The Lower Jurassic deposits have been found for the first time at Ridang, Longzi county, Southern Xizang, representing the best section for reference in the eastern Himalayas. Judging from the presence of the characteristic ammonoids, the age of these deposits seems to range, at least, from Hettangian to Pliensbachian.