The invention relates to a temporary ground wire on-line monitoring system for a transformer substation, belonging to the technical field of power monitoring equipment. The technical scheme is that the temporary ground wire on-line monitoring system comprises a temporary ground wire controller for a safe tools and instruments cabinet, a temporary ground lead pull rod, a bar code label (10), a temporary ground wire terminal state monitoring controller, a temporary ground wire terminal data controller, a triggered lantern ring (36) of the temporary ground wire terminal data controller, a triggered lantern ring lead (35) and a temporary ground wire clamp, wherein the bar code label is arranged on the temporary ground lead pull rod, the temporary ground wire controller for the safe tools and instruments cabinet, the temporary ground wire terminal state monitoring controller and the temporary ground wire terminal data controller are sequentially connected. The monitoring system provided by the invention has the beneficial effects that a temporary ground wire of the transformer substation is always in an online monitoring state, the temporary on-line monitoring system can automatically alarm to reminder persons in the transformer substation of shifting the temporary ground wire once the temperature ground wire is changed; in addition, the damage on human bodies and electric equipments caused by electric error operation accidents due to forgetting taking apart the temporary ground wire can be prevented when the temporary on-line monitoring system is operated.