With the increase in waste recycling, municipal solid waste (MSW) with high organic and moisture contents are found in various landfills worldwide. If this kind of waste were put into anaerobic condition directly, the pH values will decrease sharply, which will seriously affect the biodegradation of the wastes. This study is aimed to investigate the decomposition of the type of MSW in aerobic condition before the anaerobic biodegradation. In the study, the effects of air addition and biosolids addition on the biodegradation of MSW with high organic and moisture contents were examined. Moreover, the flushing technology was compared with the leachate recirculation technology. Six simulated bioreactor landfills were set up. After about 100 days' operation, it was observed that (1) the mass reduction rate in the aerobic-anaerobic bioreactor was approximately five times of that in the anaerobic bioreactor, the leachate quality was much better than that in the anaerobic bioreactor based on the final COD, BOD 5, TS, and NH 3 concentrations. (2) biosolids have strong buffering effects and the addition of biosolids accelerated the anaerobic biodegradation progress to a great extent. Therefore, it was concluded that initially degrading MSW under aerobic condition before anaerobic degradation with biosolids addition is the optimum strategy for the decomposition of MSW with high organic and moisture contents.