The invention discloses a systematic modification method for the steam consumption quantity of a steam turbine of a feed pump in performance tests for the steam turbine. The systematic modification method includes that the steam consumption quantity is acquired according to a formula: modified steam consumption quantity of the steam turbine of the feed pump=(water feeding flow X corresponding designed lift of a steam feed pump X the normal acceleration of gravity)/corresponding designed efficiency of the steam feed pump/(designed efficiency of the steam turbine of the feed pump X isentropic enthalpy drop of steam of the steam turbine of the feed pump). The systematic modification method has the advantages that the steam consumption quantity of the steam feed pump is modified, accordingly, the efficiency of the steam turbine of the feed pump and the efficiency of the steam feed pump are modified, and the steam consumption quantity of a steam turbine of the steam feed pump is accurately modified.