The utility model relates to a tundish molten steel buffer device, which is mounted at the bottom of a tundish directly below a long molten steel opening of a steel ladle. The tundish molten steel buffer device is characterized in that the outer wall of the buffer device is in a rectangular elliptic barrel structure; the central inner walls of the buffer device are concentric elliptic openings communicated up and down; and an elliptic shape of the lower opening is larger than that of the upper opening; joints from the bottom to the lower opening and from the lower opening to the upper opening are in arc transition; and side holes are formed in both side walls of the elliptic lower opening respectively in a long shaft direction. After molten steel is filled in the buffer device and is in contact with the bottom and the inner walls of the upper opening and the lower opening, the kinetic energy of steel flow is gradually reduced, so that the upward kinetic energy and the upward speed of the molten steel are reduced, and the impact force is remarkably reduced. Therefore, an ''eye circle'' is prevented from being formed on the melting surface of the tundish, and the secondary oxidation and the slag entrapment of the molten steel are reduced.