Abstract: With the measured data on the soft soil subgrade settlement,the curve fitting methods,hyperbolic method,exponential curve method and poisson-curve method,were Respectively taken to fit and forecast the soft soil subgrade settlement in Yangtze River floodplain,which were treated by the vacuum preloading.The results show that the exponential curve method is the best way to calculate and estimate the settlement.More importantly,the exponential curve method can be used to forecast the soft soil subgrade settlement and to guide the subgrade construction.