The method of combining air pressure with vacuum preloading has a faster effect on improving soft soil, but the duration of air pressure is too short, causing too little pore water pressure dissipation to achieve a pressure effect and if it is too long, a lot of air is in the soil which causes a decrease in vacuum which affects consolidation and soil settlement. This study aims to investigate the effectiveness of the staged air pressure with vacuum preloading (SAVP) method for soft soil improvement using a custom-designed Geo-system Air Booster Vacuum Preloading (GAVP) system. The experiment was conducted using five prefabricated vertical drains (PVDs) in a large-diameter soil sample tube, with air pressure and vacuum applied simultaneously and selectively. Settlement and pore water pressure were monitored at multiple depths in real time. The results showed that a balanced combination of air and vacuum pressure enhanced consolidation efficiency. Specifically, air pressure reduced vacuum performance and limited settlement, with optimal soft soil settlement occurring when air pressure and vacuum were in balance. This study concluded that controlled application timing and pressure balance were essential for optimizing soft soil improvement using the SAVP method.