To understand combustion characteristics of Lvliang bituminous coal slime from Shanxi Province and to study the effects of changing particle diameter and oxygen volume fraction, O₂/CO₂ combustion experiments of coal slime pellets were carried out, in which the thermocouple was used to online measure the inner temperature during the combustion process, and simultaneously the whole combustion process was monitored by a high-resolution camera. The results indicate that the dry coal slime pellets show different ignition modes at 800 ℃ under different conditions of 10%～50% O₂ concentrations. The maximum inner temperature of the coal slime pellets increases with the increasing of volume fraction, but irrelated with its diameter. The enrichment of oxygen facilitates burnout of the coal slime pellets with same particle sizes. The ignition delay time decreases as the volume fraction increases.