The influence of compaction mode on the mechanical deformation performance of coral sand foundation is examined by means of in-situ detection and settlement monitoring. The reinforcement project for coral sand foundation of an airport is taken as a case study. In line with the engineering properties of reclaimed coral sand foundation, vibratory compaction method and impact compaction method are employed in foundation treatment in different test areas. Results show that the CBR (California Bearing Ratio) could reach 38% after 20 times of vibration compaction, whereas after 30 times of impact rolling, the CBR value is only 28%. After 30 times of vibration rolling, the uncorrected characteristic value of foundation bearing capacity is above 270 kPa, the response modulus of soil foundation is up to 106.68 MN/m³, and the rolling-induced settlement deformation tends to be stable. Under the same number of times of compaction, the bearing capacity and deformation resistance of the foundation after vibration compaction are obviously higher than those after impact compaction, indicating that vibration compaction is more suitable for coral sand foundation treatment than impact compaction. The in-situ immersion test in the vibratory rolling area shows that coral sand foundation is not easily affected by surface water changes in terms of deformation properties. The research results can be used as reference in guiding the foundation treatment of reclaimed coral sand foundation and similar projects.