The invention discloses a modeling method of an auxiliary power load correction model based on measured data. The method is characterized by comprising the following steps of 1) determining a main auxiliary power medium-voltage load of a thermal power plant; 2) determining a relation between an important load and a working condition of a unit in a boiler system; 3) determining load characteristics of a medium-voltage auxiliary machine of a steam turbine system under different outputs of the unit; 4) proposing an auxiliary power static correction load model based on the auxiliary power load characteristics and simultaneously considering voltage and frequency static characteristics of an auxiliary power load; and 5) completing unknown parameters in the auxiliary power load correction model by applying a least square method on the basis of actual data of the power plant. The method has the beneficial effects that the relation between the auxiliary power load and the operation condition of the generator unit is researched on the basis of actual operation data of the power plant, the static correction model of the auxiliary power load is built according to the relation, and the deviation between a traditional auxiliary power load model result and actual data can be effectively solved; and the auxiliary power load correction model has certain reasonableness and very high precision and is of great significance to calculation of an actual power grid.