The combustion process in blast furnace (BF) has play a significant role in providing heat resources, reducing agent and primary gas flow distribution. Accordingly, large proportion energy was also consumed and discharging massive amount CO2, the most effective way to reduce that is to increase the pulverized coal injection (PCI) rate to substitute the coke and maintaining stability state of BF. But the relationship of PCI rate and raceway temperature is still unknown. In this paper, the temperature detection system based on digital imaging techniques (DIT) has been firstly applied to study the tuyere temperature regularity on various conditions in 2500 m(3) BF, such as different PCI rates, PCI cease and none PCI processes. And the colorimetric method was used to calculate the temperature distributions of tuyere images in raceway zone of BF. Moreover, the calibration, denoising and edge detection were firstly used to improve the accuracy of temperature detection. At last the influence regularity of PCI rate on the tuyere temperature was obtained. The studies not only could contribute to qualify the effect of the PCI rate on the temperature distribution in raceway zone, but also could useful to understand the pulverized coal combustion mechanism in BF raceway zone. (C) 2019 Elsevier Ltd. All rights reserved.