Abstract: In 1963 the Qilianshan Geological Reseaching Team of Academia Sinica confirmed that in the western part of North Qilianshan the Silurian was in unconformable contact with the Ordovician, and that there was a local uncon- formity between the carbonate Middle Ordovician which was named the Yao- moshan Group and the Lower Ordovician Yingou Group. In 1979 and 1981 Zhao Fengyou attributed the Yaomoshan Formation, used to replace the Yaomoshan Group, to Upper Ordovician and suggested that there was a strong orogeny- the Gulang Movement-at the end of Middle Ordovician, which caused the unconformity between the overlying Yaomoshan Formation and the underlying Zhongbao Group. In 1979--1982 the author made field observations and collected fossils in this very area but failec to find any evidence of the unconformities mentioned above. From the material thus obtained, togather with a comprehensive study of regional geological data, it is reasonable to conclude that in the western part of North Qilianshan the coontact between the Silurian and Ordovician and that between the Yaomoshan Group （Limestone） and underlying forma- tions are both conformable, and that the Yaomoshan Group contains nou only the carbonate sediment but also tts underlying volcanic series which may be the equivalent of the lower part of the Miaopo Stage.