The invention discloses an online measuring device and method for the temperature of large
blast furnace molten iron and belongs to the technical field of
temperature measurement of
blast furnace molten iron. The online measuring device comprises an iron outlet channel, a
slag skimmer, a molten iron temperature measuring unit and an
information control collector, wherein a temperature measuring mechanism is fixedly connected with the top of the
slag skimmer through a temperature measuring support; a rotating part is arranged at the top of the temperature measuring support; the other end of a horizontal telescopic rod is vertically provided with a vertical telescopic air cylinder; a temperature measuring gun is arranged at the
tail end of the vertical telescopic air cylinder and is used for installation of a temperature
thermocouple; a couple separation part is arranged at the top of the temperature measuring gun; and a
thermocouple storage mechanism and a
thermocouple fire extinguishing tank are arranged at the top of the
slag skimmer. According to the online measuring device and method, the temperature measuring time is determined by calculating the effective tapping time, complicated production conditions that a tapping hole of a
blast furnace is blocked, tapping of the tapping hole is suspended, and the blast furnace can not run smoothly are effectively handled, and the influence of subjective factors of operators is avoided, so that the online automatic measurement of the blast furnace molten iron is realized to cope with the complex production conditions.