Abstract: In order to solve the existing problems for furnace monitoring, industrial endoscope imaging resolution is low and it is susceptible to dust, which affects the accuracy of temperature measurement. A dual-channel industrial endoscope with multiple spectrum in the visible band (0.48 μm~0.65 μm) and infrared band (3 μm~5 μm and 8 μm~12 μm) was designed and processed. It had a field of view of not less than 100°, a total aperture of less than 60 mm, and a total optical length of more than 1 000 mm. The modulation transfer functions (MTF) of the optical system in the visible band, mid-wave infrared band, and long-wave infrared band are greater than 0.2 at 180 lp/mm, 30 lp/mm, and 12.7 lp/mm, respectively. After passive heat dissipation treatment, the overall optical system was less affected by the thermal difference within the temperature range of 10 ℃ to 70 ℃. The tolerance analysis results show that the designed endoscope has high-resolution imaging quality in the range of 1 m to 5 m object distance, and can distinguish 4 mm line width at 5 m. The designed industrial endoscope has been tested and verified in the factory furnace, which can effectively solve the monitoring problems in the high-temperature and dusty environment of the furnace, and improve the operational safety and production efficiency of industrial furnaces and kilns.