Abstract: The objective of this study was to analyze the effect of density on the fermentation quality and microbial content of whole plant corn (Zea mays) silage, to provide a reference for selecting the appropriate density for silage in practice. The silage material was Xinsiyu 10, which was compacted to varying densities (350, 400, 500, 600, and 700 kg/m³) and then fermented for 50 days. The fermentation quality, microbial content, and aerobic stability of silage samples after 12, 24, 36, 60 and 108 h exposure to air were evaluated using an online multi-channel data logger temperature recorder. The results indicated that the pH value, lactic acid content, acetic acid content, NH₃-N content, and amounts of lactic acid bacteria, molds, yeasts, and aerobic bacteria significantly decreased during ensilage (P<0.05). Oxygen exposure time had a significant effect on the above indicators (P<0.01) during aerobic exposure. At 108 h after opening silos, the 600 kg/m³ treatment had the highest lactic acid bacteria content (up to 8.17 lg cfu/g FW) and the lowest pH value, NH₃-N content, fungi content (5.38 lg cfu/g FW) and yeasts content (7.72 lg cfu/g FW). The 600 kg/m³ treatment also showed the highest stability among the treatments (100 h in air; P<0.05). In summary, these results indicate that 600 kg/m³ is the best density for producing corn silage with high fermentation quality and aerobic stability.