Under the context of carbon peaking and carbon neutrality goals, oxygen-enriched combustion combined with flue gas circulation technology represents the development direction of new processes for future cement firing systems. Oxygen-enriched air entering the rotary kiln through different inlet methods affects the thermal regime of the rotary kiln differently. To compare the effects of various oxygen-enriched air inlet methods, this paper employs numerical simulation to investigate their influence on temperature distribution, peak temperature, and NOX generation in the rotary kiln. When oxygen is predominantly introduced through the primary air, the variation trends of the temperature field, temperature peak, and NOX generation in the kiln align with those caused by increasing the oxygen-enriched percentage. However, excessive oxygen enrichment in the primary air will lead to a significant increase in NOX generation, shorten the length of the high-temperature zone, and reduce temperature uniformity in the kiln. The effect of oxygen entering the kiln through primary air is better than that through secondary air, and the oxygen enrichment percentage of primary air should be reasonably controlled in actual use.