A firmware upgrade method for a slave station of a robot communicates with a master station of the robot via an EtherCAT bus of the robot, includes: switching a work mode of the slave station to an upgrade mode in response to a firmware upgrade instruction, receiving a new firmware corresponding to this firmware upgrade via the EtherCAT bus, storing the new firmware in a second storage area of a flash memory of the slave station, restarting the slave station after the new firmware is received, and copying the new firmware stored in the second storage area to a first storage area of the flash memory and executing the new firmware in the first storage area when the slave station is started. A slave station of the robot and a machine readable storage medium are also provided.