The essence of vacuum combined surcharge preloading method is to combine negative pressure consolidation theory of vacuum preloading method with positive pressure consolidation theory of surcharge preloading method, and to make the soil’s consolidation maximization. The average degree of consolidation calculation method based on pore water pressure and settlement is put forward by theoretical analysis under surcharge preloading condition. Combining with large-area blown filled muck soft foundation treatment engineering practice, loading rate and loading cycle are put forward by observing the pore water pressure and settlement. The pore water pressure change law is studied, and checking calculation of the average degree of consolidation is analyzed combining with engineering practice, and it is proved that the method is reasonable.