Abstract: Using the math calculate program of Different Physical Mode Method(DPMM),choosing water-vapour flux divergence(moist potential vorticity) forecast deviations integraled 48h on 500hPa to construct normalization initial value disturbance mode of initial value disturbance,and it constructs disturbance initial value,makes a ensemble forecast test on a heavy rain case in Northeast,gives comparative analysis on the results of two kinds of physical quantity approaches from horizontal structure of disturbance initial value,ensemble forecast average,precipitation rate over 50mm,precipitation dispersion,region forecast deviations,Talagrand probability distribution,Brier Score,hourly variance evolution of ensemble forecast system on control forecast,and other aspects.It considers that the results of two kinds of approaches are similar in general,and there is no significant difference.The initial value disturbance differences produced from two kinds of approaches do not cause the difference of large-scale circulation,but affect the mesoscale dynamic field and thermodynamic field.On Brier Score and rain belt location,the water-vapour flux divergence approach is slightly better than moist potential vorticity approach,but on heavy precipitation range,the moist potential vorticity approach is slightly better.Besides,the forecast deviations show that the dispersion of ensemble forecast system of moist potential vorticity approach is bigger.