Abstract: This paper discusses the distribution type,characteristics and homogenization temperature of fluid inclusion in reservoir systematically on the basis of analyzing the tectonic evolution of Yancheng Depression,the trap formation and evolution of Zhujiadun structure and the genetic and expulsive characteristics of main source rock in Yancheng Depression.It shows in our study that the fluid inclusion in K₂t reservoir can be obviously classified into saline water inclusion and organic inclusion and the homogenization temperature,and can be obviously classified into two stages(the corresponding geological time is Late Oligocene and the end of Neogene).Combing with the tectonic evolution hydrocarbon history,trap development history and genetic and expulsive hydrocarbon history,it is thought there are two stages gas filled in Zhujiadun gas reservoir in Late Oligocene and the end of Neogene,between which the Late one is more important.