Abstract: Acoustic propagation uncertainty cannot be studied directly by using Monte Carlo method with few measured sound speed profiles (SSPs) in shallow waters. The extrapolating vector method based on empirical orthogonal function (EOF) method is proposed for obtaining the extrapolated SSP with the same statistics as those of the measured SSPs, and then the probability density function (PDF) of transmission loss (TL) is calculated with the extrapolated SSP based on Monte Carlo method. The results demonstrate that the elements of extrapolating vector should satisfy standard normal distribution, and SSPs which are not measured experimentally but possibly exist are captured in the extrapolated data. The proposed method provides a new way to analyze uncertainty of acoustic propagation with few measured SSPs in shallow waters.