The invention discloses a runner fixing device. The runner fixing device comprises a first connecting fixing plate, the first connecting fixing plate comprises a first horizontal fixing plate and a first convex part arranged on the first horizontal fixing plate, a second connecting fixing plate comprises a second horizontal fixing plate and a second convex part arranged on the second horizontal fixing plate, a heat insulation structure comprises a vertical heat insulation wall, a third convex part arranged at the top end of the vertical heat insulation wall and a fourth convex part arranged atthe bottom end of the vertical heat insulation wall, an outer shell comprises a vertical shell body, a fifth convex part arranged at the top end of the vertical shell body and a sixth part arranged at the bottom end of the vertical shell body; the first connecting fixing plate and the second connecting fixing plate are arranged up and down, the first convex part and the second convex part are coaxial in the vertical direction, the co-axis is named as a center axis, and the runner fixing device forms a central symmetry structure by taking the center axis as the center. The loss of cold heat isreduced in the environment test, the aeolian vibration is reduced, the stress damage caused by thermal deformation or resonance is reduced, and the defect of instable structure caused by different thermal deformation of the runner shell body and an external steel structure is overcome.