The invention discloses a ball seat, and belongs to the technical field of oilfield flooding. The ball seat comprises a tubular upper connector, an outer
barrel, a core
pipe, a self-locking
shear pin, a clamp spring, a check ring and a lower connector, wherein the upper connector and the lower connector are both connected with the outer
barrel; an inner cavity of the lower connector is provided with a first inclined surface; an inner cavity of the core
pipe is provided with a second inclined surface and the core
pipe is connected with the outer
barrel through the self-locking
shear pin; the core pipe is provided with a first clamp spring groove, and the clamp spring is arranged in the first clamp spring groove; an inner cavity of the check ring is provided with a third inclined surface and shaped like a calabash formed by overlapping two communicating cylindrical cavities with the same
diameter, the width of the overlapping surface is smaller than the
diameter of a thrown ball, and the
diameter of the cylindrical cavities is larger than the diameter of the thrown ball; a step is arranged on the wall of an inner cavity of the outer barrel; the upper end of the check ring and the step are coplanar, and the lower end of the check ring and the upper end of the lower connector are coplanar; and a second clamp spring groove is formed in the outer barrel, the self-locking
shear pin is shorn off, the core pipe moves downwards, and the clamp spring is clamped in the second clamp spring groove. By means of the ball seat, the problems that the thrown ball is difficult to throw and returns to cause sealing failure of a water injection pipe column are solved, and the effect of effectively sealing the water injection pipe column is realized.