The carbonates of the third Member of Ordovician Majiagou Formation in northwestern Henan host plenty of trace fossils. Based on the field observation and measurement for the trace fossils, this study analyzed the ichnofabrics and sedimentary evolution using rock slice and thin section. The results present as follows. Trace fossils from the third Member of Ordovician Majiagou Formation in northwestern Henan consist of at least 7 ichnogenera and 10 ichnospecies. Four ichnofabrics were identified according to the composition and occurrence characteristics, 〖JP2〗abundance and diversity of trace fossils as well as bioturbation index. ① The Psilonichnus ichnofabric is mainly developed in lowenergy sedimentary environment between supratidal zone and high tide flat of intertidal zone. ② The Thalassinoides ichnofabric indicates a highenergy sedimentary environment between the middle and lower part of the intertidal zone as well as beach in carbonate platform. ③ The Helminthopsis ichnofabric suggests 〖JP〗a relatively lowenergy sedimentary environment such as lagoon in restricted carbonate platform of interbank sea. ④ The HelminthopsisChondrites ichnofabric develops in a low energy sedimentary between interbank sea and depression of open carbonate rock platform. The sequence stratigraphic framwork of the thirdmember of Majiagou Formation was set up and a research about the evolution of ichnofabrics and sedimentary microenvironment was completed, which suggests that the third member of Majiagou Formation experienced two regional transgressiveregressive events. Based on types of rocks, combination of rock sequence, sediment structure, body fossils, combination of trace fossils and ichnofabrics in the thirdmember of the Majiagou Formation, along with the carbonate sediment model of Tuck (1974) which is appropriate for North China Basin, this study established the 3D facies model of ichnofabrics and sediment microenvironment in the thirdmember of Ordovician Majiagou Formation. This study has great reference significance in reconstructing the Ordovician sedimentary environment and paleogeography of North China Basin.