High moisture and volatile content of lignite are not conducive to transportation and storage, and can reduce boiler combustion efficiency. As a common technology for lignite upgrading, low-temperature torrefaction and upgrading can effectively reduce moisture in fuel and improve fuel quality, significantly change the combustion characteristics of lignite. In the diffusion-flamelet-based Hencken burner experimental facility, the effect of torrefaction temperature (200, 250 and 300 ℃) on the ignition and combustion characteristics of lignite were carried out via CMOS camera. The effect of the co-flow temperatures (1 473, 1 673 and 1 873 K), oxygen concentrations (5%, 10% and 20%) were considered. Results show that the ignition delay distance of torrefacted lignite particles is slightly larger than that of raw lignite particles under the same co-flow temperature and oxygen concentration. Under the oxygen concentration of 5%, the ignition delay distance of the torrefacted lignite at 200 ℃ are increased by 0.24, 0.28 and 0.13 cm when comparing with that of the raw lignite particles, respectively. Additionally, the increase of torrefaction temperature significantly decreases the ignition delay distance of lignite particles. Under case of 1 673 K and 5% O2, the ignition delay distance of torrefacted lignite at 200, 250 and 300 ℃ are increased by 0.28, 0.16 and 0.11 cm when comparing with that of raw lignite, respectively.