A partition plate, a battery module, a battery pack, and a device. The partition plate is applied to the battery module. The partition plate includes: a first assembling piece, configured to overlay one battery cell of the battery module, where the first assembling piece includes a first body portion and a first connecting portion disposed around the first body portion; and a second assembling piece, disposed alongside the first assembling piece, and configured to overlay another battery cell of the battery module, where the second assembling piece includes a second body portion and a second connecting portion disposed around the second body portion. The first assembling piece and the second assembling piece are spliced to each other through coordination between the first connecting portion and the second connecting portion.