The present invention provides a method and a system for supplying lithium to an electrode plate. The method includes: compositing a first substrate and a first lithium strip to form a first composite lithium strip, and forming an obstruction using a second substrate between the first lithium strip and a compositing device, compositing the first composite lithium strip and an electrode plate to be supplied with lithium to form a lithium supplied composite electrode plate, during the compositing process, the first substrate in the first composite lithium strip is located at a side away from the electrode plate to be supplied with lithium, peeling and reeling the first substrate from the lithium supplied composite electrode plate, to form a lithium supplied electrode plate.