The present disclosure relates to a cap assembly and a secondary battery. The cap assembly includes a cap plate provided with an electrode lead-out hole; an electrode terminal, covering the electrode lead-out hole and including a main body, wherein the main body is provided with a recess on a side wall; an isolating member including a receiving portion, wherein the main body is received in the receiving portion; and a protrusion, connected to an inner wall of the isolating member and extending towards an axis of the electrode lead-out hole, wherein the protrusion is received in the recess so as to prevent the main body from rotating relative to the isolating member. The cap assembly according to the embodiments of the present application can improve an overcurrent capacity and stability of the electrode terminal.