Abstract: The stability of the old landslide of Guizhou in the Three Gorges region during reservoir water level drawdown from 175 to 145m is studied.Using the Golden-Split method to optimize the calculating process,the stability of the old landslide of Guizhou during reservoir water level drawdown is analyzed in combination of the pore water pressures calculated from the transient seepage analyses by using the finite element software MIDAS/GTS.Through numerical calculation,the relationships between the landslide stability and the reservoir water level drawdown are obtained.The results show that the old landslide of Guizhou is stable during the reservoir water level drawdown from 175 to 145m.It is effective to apply Golden-Split method to the analysis of landslide stability on a reservoir region.A minimum value of the safety coefficient of landslide exists,which does not singly reduce with reservoir water level drawdown.