The invention discloses an on-line treatment method of electric power steam turbine oil with foam characteristic exceeding a standard. The on-line treatment method comprises a lab regeneration treatment test adsorbent use amount analysis, on-line treatment on steam turbine oil with foam characteristics exceeding a standard, and antifoaming agent addition. The on-line treatment process can be carried out in turbine operation, does not influence normal production and thoroughly solves the problem that the steam turbine oil foam characteristic exceeds a standard. The on-line treatment method has the advantages of simple processes, operation easiness, cost saving and obvious effects and is suitable for on-line treatment on electric power steam turbine oil with foam characteristic exceeding a standard.