A method for testing a mechanical performance of a lithium ion battery electrode based on a nano-indentation technology includes following steps: connecting an assembled lithium ion battery with an electrochemical test device and setting different test working conditions, so that cyclic charge and discharge experiments are performed on the battery to obtain an attenuation curve of a battery capacity; disassembling the battery and taking out the electrode; scraping some powder from a surface of the cyclic electrode plate and an initial uncyclic electrode plate, and laying down the powder in cold mounting molds separately, pouring the cold mounting solution into the molds; taking out the samples from the molds respectively after the liquid is completely cured and cooled; detecting a mechanical performance after polishing the samples surfaces and analyzing the mechanical performance decay rule of the electrodes.