Macaronichnus segregatis in the Shahejie Formation of Paleogene in Chezhen Sag of Jiyang Depression is an intrastratal and irregularly meandering burrow structureIt is 7~8 mm in length and 1~3 mm in diameter,which is different in size from the same genus formerly discoveredThe ichnotaxon is commonly distinguished from several sedimentary environments:①places between channels of delta plain; ②delta,fan delta front bar and middle to outer fan of turbidite fan; ③shallow lake under humid climate;and ④shore to shallow lake sediments under periodically arid climateThey are generally found in silty mudstone deposited in different environmentsBased on the analyzed results of the hydrodynamic conditions,the chemical characters in different sedimentary environments and the forming process of Macaronichnus segregatis,some conclusions can be drawn as following: ① Msegregatis occurs in moderate water energy environments,and rather high or low water energy is not suitable for its existence;② The burrowmaker of Msegregatis lives among the upper dysoxic zone;③ Msegregatis is produced by depositfeeder before the substrate becomes firm,implied by the presence of linings surrounding the trace fossils