A large-scale semi-aerobic landfill set (21 m x 3.8 m x 6.0 m) was constructed to study the variation characteristics of pollutants in the landfill leachate. The results showed that after 39 weeks, the concentrations of CODCr, BOD5 and NH3+-N in the leachate declined rapidly, which reached 173, 30 and 15 mg x L(-1) respectively, and the reducing rate of NH3+-N was 99.6%. The pH value was below 7 during the first 2 weeks, but became weak alkaline after three weeks. Based on the experimental data, the attenuation equations of pollutants in the leachate were built.