The invention relates to an on-line monitoring and closed-loop regulating abnormity control system for a high back pressure heat supply working condition. The on-line monitoring and closed-loop regulating abnormity control system comprises a heat supply unit and a control system body, wherein the heat supply unit comprises a condenser, an intercooling tower and a circulating water system; blind windows are arranged in the intercooling tower; circulating water is introduced to the condenser from the A side, heat supply network water is introduced to the condenser from the B side; the circulating water is cooled through the intercooling water; the circulating water system comprises a variable frequency circulating water pump and a constant speed circulating water pump which are arranged between the intercooling tower and the A side of the condenser in a parallel manner; the control system body comprises a DCS system, an industrial personal computer (IPC) and an OPC interface machine; the IPC is connected with the DCS system through the OPC interface machine; and the IPC collects the real-time operation data of the heat supply unit through the DCS system and sends a frequency instruction value to the frequency converter of the variable frequency circulating water pump and a blind window opening degree instruction value to the blind windows through the DCS system according to the real-time operation data and the made control strategy. The on-line monitoring and closed-loop regulating abnormity control system for the high back pressure heat supply working condition has the benefit that through abnormity control, safe and economic operation of the high back pressure heat supply unit is ensured.