This paper presents a numerical simulation study on a low NOx burner for a lime rotary kiln. The simulation employs the Realizable k-ε model for turbulence, the finite rate/eddy-dissipation model for combustion, the P-1 model for radiation, and the extended Zeldovich mechanism and Fenimore mechanism for NOx formation. The results show that the flame in the kiln exhibits a ring-shaped distribution with a low central temperature and high peripheral temperatures. The combustion process is relatively slow, with a small high-temperature region in the initial stage and a more complete combustion in the later stage. The NOx concentration at the kiln exit is 369 mg/m3, exceeding the emission limit set by Liaoning Province. The analysis reveals that the burner does not achieve sufficient mixing of fuel and air, leading to slow combustion, localized high temperatures, and high NOx emissions. To address these issues, optimization of the burner’s structural parameters and the kiln’s operating parameters is proposed. Future research will focus on investigating the effects of parameters such as fuel staging, air staging, swirl number, secondary air preheating temperature, secondary air ratio, secondary air supply mode, and flue gas recirculation rate on the combustion process and NOx emissions.