The invention discloses a ball-milling tank and a method for preparation of rare gas in a rock inclusion. The ball-milling tank for preparation of rare gas in the rock inclusion comprises a sample tank, a high vacuum valve and a heating component, wherein the sample tank comprises a tank body and a top cover arranged on the upper part of the tank body in a sealing way, the tank body is provided with an accommodating cavity, and more than one first steel ball is arranged in the accommodating cavity; the high vacuum valve is connected with the top cover, the top cover is provided with a through hole, and a gas inlet of the high vacuum valve is communicated with the accommodating cavity of the tank body through the through hole; and the heating component is sleeved outside the tank body of the sample tank. By adopting the ball-milling tank and the method for preparation of the rare gas in the rock inclusion, impurity gases and moisture on the surface of a rock inclusion sample can be removed, the sealing state can be always maintained when the rock inclusion sample is ball-milled, and the prepared rare gas cannot be polluted by rare gases in external air.