In this study,a denitrification(DN)-partial nitritation(PN)-anaerobic ammonia oxidation(Anammox)system for the efficient nitrogen removal of mature landfill leachate was built with a zone-partitioning self-reflux biological reactor as the core device,and the effects of changes in seasonal temperature on the nitrogen removal in non-temperature-control en-vironment were explored.The results showed that as the seasonal temperature decreased from 34℃to 11.3℃,the total nitrogen removal rate of the DN-PN-Anammox system gradu-ally decreased from the peak value of 1.42 kg/(m3·day)to 0.49 kg/(m3·day).At low tempera-tures(＜20℃),when the nitrogen load(NLR)of the system is not appropriate,the fluctuation of high NH4+-N concentration in the landfill leachate greatly influenced the stability of the nitrogen removal.At temperatures of 11℃-15℃,the NLR of the system is controlled below 0.5 kg/(m3·day),which can achieve stable nitrogen removal and the nitrogen removal effi-ciency can reach above 96％.The abundance of Candidatus Brocadia gradually increased with the decrease of temperature.Nitrosomonas,Candidatus Brocadia and Candidatus Kuenenia as the main functional microorganisms in the low temperature.