In view that the theoretical research on the vacuum-surcharging preloading technique for reinforcing marine soft soil subgrade is lagged behind the engineering practice,we analyze the variation law of the surface settlement and environmental effect in the process of strengthening of marine soft soil subgrade by the vacuum-surcharging preloading method,which is based on the field monitoring data.The results show that the vacuum-surcharging preloading treatment can speed up the rate of foundation settlement and shorten the construction period;inward lateral displacements chiefly occur at 2 m below the ground during the vacuum preloading stage;the reinforced soil more easily to produce the lateral extrusion deformation outside the reinforcement area during the preloading stage and the horizontal soil environmental influence scope is more than 8 m.