A temperature measurement method for a fluid in a steady flow field, wherein the method comprises: placing a first sensing junction of a first thermocouple into the fluid and obtaining a first temperature through a first instrument electrically connected to the first thermocouple, the first thermocouple having a first wire and a second wire joined to form the first sensing junction; acquiring a second temperature at a first position on the first wire using a second thermocouple and a second instrument electrically connected to the second thermocouple; and characterized by acquiring a third temperature at a second position on the second wire using a third thermocouple and a third instrument electrically connected to the third thermocouple; the first thermocouple being subjected to several different thermal equilibrium states during a temperature measurement, the first temperature, the second temperature, and the third temperature being obtained in each thermal equilibrium state, the number of thermal equilibrium states experienced during the temperature measurement being greater than or equal to the number of unknown variables in a variable set including a fluid temperature, an emissivity of the first wire, an emissivity of the second wire, an absorbed irradiation by the first wire, an absorbed irradiation by the second wire, a convection heat transfer coefficient between the first wire and the fluid, and a convection heat transfer coefficient between the second wire and the fluid; the first wire between the first sensing junction and the first position being divided into at least two first elements along an extension direction of the first wire; the second wire between the first sensing junction and the second position being divided into at least two second elements along an extension direction of the second wire, and energy conservation equations being established for the first sensing junction and all first and second elements in each thermal equilibrium state, with all unknown variables in the variable set being involved in the energy conservation equations of all thermal equilibrium states, and with all energy conservation equations of all thermal equilibrium states being solved together to obtain values of the unknown variables including the fluid temperature. placing a first sensing junction of a first thermocouple into the fluid and obtaining a first temperature through a first instrument electrically connected to the first thermocouple, the first thermocouple having a first wire and a second wire joined to form the first sensing junction; acquiring a second temperature at a first position on the first wire using a second thermocouple and a second instrument electrically connected to the second thermocouple; and characterized by acquiring a third temperature at a second position on the second wire using a third thermocouple and a third instrument electrically connected to the third thermocouple; the first thermocouple being subjected to several different thermal equilibrium states during a temperature measurement, the first temperature, the second temperature, and the third temperature being obtained in each thermal equilibrium state, the number of thermal equilibrium states experienced during the temperature measurement being greater than or equal to the number of unknown variables in a variable set including a fluid temperature, an emissivity of the first wire, an emissivity of the second wire, an absorbed irradiation by the first wire, an absorbed irradiation by the second wire, a convection heat transfer coefficient between the first wire and the fluid, and a convection heat transfer coefficient between the second wire and the fluid; the first wire between the first sensing junction and the first position being divided into at least two first elements along an extension direction of the first wire; the second wire between the first sensing junction and the second position being divided into at least two second elements along an extension direction of the second wire, and energy conservation equations being established for the first sensing junction and all first and second elements in each thermal equilibrium state, with all unknown variables in the variable set being involved in the energy conservation equations of all thermal equilibrium states, and with all energy conservation equations of all thermal equilibrium states being solved together to obtain values of the unknown variables including the fluid temperature.