A cap assembly of a power battery comprises: a cap plate, a first electrode terminal provided to the cap plate, and a resistance member electrically connected to the cap plate and the first electrode terminal. The resistance member comprises: a heat-resistant insulating base body positioned between the cap plate and the first electrode terminal; and a heat-resistant metal layer provided to a circumferential side of the heat-resistant insulating base body. The heat-resistant metal layer and the cap plate and the first electrode terminal are electrically connected to form a conductive path. The formed conductive path is a curved path, therefore the resistance value of the resistance member can be controlled by controlling the conductive path.