The utility model provides an it exchanges ATS switch on -line monitoring system to stand to press with step -down, includes: phase sequence comparator, phase comparator, monitoring host, testing arrangement. Phase sequence comparator both ends insert respectively that 1# station becomes the current transformer that is qualified for the next round of competitions, the 2# station becomes the current transformer that is qualified for the next round of competitions, the phase comparator both ends insert respectively that 1# station becomes the voltage transformer that is qualified for the next round of competitions, the 2# station becomes the voltage transformer that is qualified for the next round of competitions. Phase sequence comparator, the equal connection monitoring host computer of phase comparator. Monitoring host connect respectively the low -voltage wire inlet position of the switch that 1# station becomes open the low -voltage wire inlet position of the switch that off state monitor, 2# station become drive the off state monitor. The utility model relates to an it exchanges ATS switch on -line monitoring system to stand to press with step -down, effectively the monitoringstation is with the operation that becomes the ATS switch, and each item operating data of real -time supervision and conveying ATS switch checks with the phase place phase sequence that the power iscarried out in the interchange that becomes the station in real time, ensures that the ATS switch can normally switch, can not lead to the station to close the ring and move with becoming.