1. A system for controlling a robot by brain electrical signal, comprising: a screen to show a plurality of icons thereon, and the plurality of icons being configured to flash at different frequencies, an electrical signal detection device to detect brain electrical signal of an operator when one of the plurality of icons is stared at by the operator; an host computer storing a plurality of personal reference parameters corresponding to the plurality of icons of the screen, the host computer being configured to process the brain electrical signal to get parameters of use, and comparing the parameters of use with the plurality of personal reference parameters to choose the icon which is stared at and to control the robot to execute works represented by the icon.