A battery pack, comprising a first battery module , a second battery module and a box body , wherein the first battery module and the second battery module are housed in the box body ; wherein the box body comprises a lower box body configured to support the first battery module and the second battery module , and an upper box body fitting with the lower box body ; the lower box body comprises a first connecting portion , the first connecting portion is located between the first battery module and the second battery module , the upper box body comprises a second connecting portion , and the first connecting portion and the second connecting portion are fixed and connected; wherein the first connecting portion of the lower box body has a first protrusion portion protruding upward along a height direction (H), and the first protrusion portion of the first connecting portion is fixed and connected to the second connecting portion of the upper box body ; wherein the second connecting portion of the upper box body has a second protrusion portion protruding downward along the height direction (H), and the first protrusion portion of the first connecting portion is fixed and connected to the second protrusion portion of the second connecting portion ; and characterized in that the first protrusion portion of the first connecting portion is formed with a first recess (R1) recessed inward along the height direction (H), and the first recess (R1) and the second protrusion portion of the second connecting portion are fixed and connected by concave-convex fit; or the second protrusion portion of the second connecting portion is formed with a second recess (R2) recessed inward along the height direction (H), and the second recess (R2) and the first protrusion portion of the first connecting portion are fixed and connected by concave-convex fit. wherein the box body comprises a lower box body configured to support the first battery module and the second battery module , and an upper box body fitting with the lower box body ; the lower box body comprises a first connecting portion , the first connecting portion is located between the first battery module and the second battery module , the upper box body comprises a second connecting portion , and the first connecting portion and the second connecting portion are fixed and connected; wherein the first connecting portion of the lower box body has a first protrusion portion protruding upward along a height direction (H), and the first protrusion portion of the first connecting portion is fixed and connected to the second connecting portion of the upper box body ; wherein the second connecting portion of the upper box body has a second protrusion portion protruding downward along the height direction (H), and the first protrusion portion of the first connecting portion is fixed and connected to the second protrusion portion of the second connecting portion ; and characterized in that the first protrusion portion of the first connecting portion is formed with a first recess (R1) recessed inward along the height direction (H), and the first recess (R1) and the second protrusion portion of the second connecting portion are fixed and connected by concave-convex fit; or the second protrusion portion of the second connecting portion is formed with a second recess (R2) recessed inward along the height direction (H), and the second recess (R2) and the first protrusion portion of the first connecting portion are fixed and connected by concave-convex fit. <EOS>