Compaction grouting, an in-situ static compaction technique by means of grout injection, has been increasingly adopted for improving the liquefaction resistance of loose sandy ground in recent years. An increase in the lateral confining pressure and densification are considered as the main factors for the increase in the liquefaction resistance of sand caused by compaction grouting. The advantage of this method is that the construction can be conducted without disturbing the existing and servicing structures such as airport runways and taxiways. However, several issues, such as high cost of construction compared to another liquefaction countermeasure such as sand compaction pile method or damaging pavements caused by unexpected ground surface heaves, has also been reported. The present study addresses these issues by investigating the effect of the improvement ratio or grout pile spacing of compaction grouting on the liquefaction resistance by model tests using a geotechnical centrifuge and X-ray tomography and numerical simulations. The findings indicate that the densification can be archived mainly in the lateral side of a grout pile and high earth pressure coefficient value, K, provides effective liquefaction resistance to the sandy ground.