The present invention discloses a cooling apparatus. The cooling apparatus comprises a seat body adapted to be mounted on a housing of an electric spindle. The seat body is provided with a liquid inlet passage and a liquid outlet passage therein, wherein the liquid inlet passage and the liquid outlet passage are communicated with the interior of the electric spindle. The seat body is in an annularshape, and has an avoidance space, or an avoidance passage, or an avoidance opening to avoid the dynamic balance tooling position of the electric spindle. The cooling apparatus can avoid the dynamicbalance tooling position of the electric spindle, and has high work efficiency. In addition, the cooling apparatus can effectively improve processing accuracy of the electric spindle.