Abstract: The sound field vertical correlations as functions of vertical spans and ranges in sloping bottom environment are studied by way of numerical simulations and experimental data analysis. The experiment was conducted in the continental shelfbreak in the South China. The wedge mode theory is used to explain the numerical and experimental results. It is shown that there are much difference of the sound field vertical correlation between the upsloping sea bottom and the downsloping sea bottom. In comparison to a flat-bottomed sound channel, a downslope bottom induces increase the vertical coherence and upslope bottom induces decrease the vertical coherence. Oscillating phenomenon of the vertical correlations produced by the interference between normal modes is observed, and the upslope bottom and downslope bottom will decrease or increase the radius of the oscillation.