The present disclosure provides a battery cap assembly, a secondary battery and a battery module. The battery cap assembly comprises: a cap plate, including a second terminal hole; a first electrode terminal, at least a part of which protruding above the cap plate; a second electrode terminal, including a second protruding portion protruding above the cap plate and a second base portion connected with the second protruding portion. The first electrode terminal is provided with a protrusion used for welding with a first connecting piece; the second protruding portion is used for welding with a second connecting piece to form a welding portion, and a projection of the welding portion in an up-down direction is positioned in a cross-section of the second base portion. The secondary battery comprises a case, an electrode assembly and the battery cap assembly. The battery module comprises the first connecting piece and the secondary batteries.