A stirring apparatus of an ingot casting furnace includes a rotating shaft and at least one fin. The fin is provided onto the rotating shaft, and has a first edge, a second edge of unequal length provided correspondingly, and a third edge connecting the first and the second edges. The rotating shaft can be driven to rotate, which consequently drives the at least one fin to stir materials in a crucible. The length of the first edge is different from that of the second edge in order for the materials in the crucible can be mixed with dopants more uniformly during the stirring process to produce ingots of stable quality.