Abstract: Based on the cores observation and description as well as the geological setting research, the seismite is identified in the Yaojia formation of Cretaceous in Gulong sag of Songliao basin, and the seismite sequence in this area is established. The seismite is characterized by such marks as liquefied sandstone dikes, seismic fissures, micro?faults, discordant blocks, load casts, eye?like structures, etc. The discovery of seismite is helpful to analyze the sedimentary environment and structural evolution in this area, and the seismic activity has a significant effect on hydrocarbon accumulation. It can reduce the porosity and permeability of reservoirs, cause rupture of some consolidated or tight rocks; it can destroy the cap rocks and improve the reservoir quality; the permeability of reservoir and cap rocks can be greatly effected by the vertical sandstone dikes, micro?faults and fissures caused by seismic actions, accordingly, the oil and gas migration and accumulation could be effected by them