A header assembly, comprising: a collecting plate, wherein the collecting plate comprises a collecting plate body, and at least one collecting channel and a plurality of slots arranged on the collecting plate body, and each of the slots is in communication with the at least one collecting channel, and the at least one collecting channel has one end closed and the other end open, along a thickness direction of the collecting plate; and a cover plate, which is stacked on and connected to the collecting plate to seal the other end of the at least one collecting channel, wherein the collecting plate body comprises a base plate and a main plate which are arranged separately, each of the plurality of slots is arranged running through the base plate, the at least one collecting channel comprises a through groove arranged running through the main plate, and the base plate is connected to one side of the main plate to close one end of the through groove, and the cover plate is connected with the other side of the main plate to seal the other end of the through groove; the collecting plate further comprises at least one protrusion portion, which is arranged on a side wall of the at least one collecting channel and fixedly connected to the base plate; a plurality of protrusion portions are provided, and the plurality of protrusion portions are arranged at intervals along an extension direction of the collecting plate, and the plurality of slots and the plurality of protrusion portions are arranged as staggered, in the extension direction of the collecting plate; the at least one collecting channel comprises a first collecting channel, the at least one protrusion portion comprises communicating protrusion portions provided in the first collecting channel, the plurality of communicating protrusion portions are configured to divide the first collecting channel into one conducting groove extending along a length direction of the collecting plate and a plurality of flow guiding grooves communicating with the conducting groove; and the flow guiding grooves are arranged directly opposite to the corresponding slots; each of the communicating protrusion portions comprises two protrusions, and the two protrusions are respectively disposed on two side walls of one of the at least one collecting channel, and an interval is provided between the two protrusions with the interval forming the conducting groove; and the plurality of slots are divided into a plurality of slot columns arranged side by side, and the at least one collecting channel comprises plural collection channels which are arranged side by side, wherein any one of the collecting channels is arranged corresponding to a corresponding one of the slot columns, characterized in that the interval between the two protrusions is arranged obliquely with respect to the extension direction of the collecting plate. a cover plate, which is stacked on and connected to the collecting plate to seal the other end of the at least one collecting channel, wherein the collecting plate body comprises a base plate and a main plate which are arranged separately, each of the plurality of slots is arranged running through the base plate, the at least one collecting channel comprises a through groove arranged running through the main plate, and the base plate is connected to one side of the main plate to close one end of the through groove, and the cover plate is connected with the other side of the main plate to seal the other end of the through groove; the collecting plate further comprises at least one protrusion portion, which is arranged on a side wall of the at least one collecting channel and fixedly connected to the base plate; a plurality of protrusion portions are provided, and the plurality of protrusion portions are arranged at intervals along an extension direction of the collecting plate, and the plurality of slots and the plurality of protrusion portions are arranged as staggered, in the extension direction of the collecting plate; the at least one collecting channel comprises a first collecting channel, the at least one protrusion portion comprises communicating protrusion portions provided in the first collecting channel, the plurality of communicating protrusion portions are configured to divide the first collecting channel into one conducting groove extending along a length direction of the collecting plate and a plurality of flow guiding grooves communicating with the conducting groove; and the flow guiding grooves are arranged directly opposite to the corresponding slots; each of the communicating protrusion portions comprises two protrusions, and the two protrusions are respectively disposed on two side walls of one of the at least one collecting channel, and an interval is provided between the two protrusions with the interval forming the conducting groove; and the plurality of slots are divided into a plurality of slot columns arranged side by side, and the at least one collecting channel comprises plural collection channels which are arranged side by side, wherein any one of the collecting channels is arranged corresponding to a corresponding one of the slot columns, characterized in that the interval between the two protrusions is arranged obliquely with respect to the extension direction of the collecting plate.