Abstract：Based on the composition and distribution characteristics of lithological characters, sedimentary structures, body fossils and ichnofossils in the Middle Ordovician Majiagou Formation within Black Dragon Canyon, Yuntai Mountain World Geopark, Jiaozuo area, detailed research on the sedimentary environment and evolution have been got.It shows that the Majiagou Formation in the study area mainly consists of the tidal-flat and carbonate platform deposits, which can be divided into two major sedimentary facies including tidal-flat facies and carbonate platform facies, and three depositional subfacies such as supratidal zone, intertidal zone and subtidal open platform.The sedimentary evolution of the Majiagou Formation in the study area experienced seven sea-level change cycles, each of the cycle begins from the deposit of intertidal zone (or supratidal zone) , change into the deposit of subtidal open platform while the sea water gradually becomes deeper, and then turn into the deposit of intertidal zone when the sea water continuously becomes shallower, seven times of sea level change process in the sedimentary period of the Majiaogou Formation can be recognized.It is of great significance to study on the depositional environment and evolution in the Majiagou Formation of the Black Dragon Canyon in recovering the sedimentary environment in early Palaeozoic as well as enriching the geological information in Yuntai Mountain World Geolpark.

Keyword：Black Dragon Canyou;Ordovician;Majiagou Formation;carbonate rock;