There were two episodes during which fluids migrated in the Big Daqing Anticline (BDA), Songliao Basin. The first-episode inclusions represent the fluid migrating in reservoir. The second episode represents fluid activity dominated by the tectonic movement and closely related to large-scale migration of fluid. Due to the fact that the fluid activity in the second episode was closely related to Yanshanian tectonic activities, this paper suggests that the rapid effective charge of gas and oil in the BDA was mainly subject to tectonics, ie. episodic gas and oil migration and accumulation was controlled by the tectonics.