Abstract: In the extraction processes of some pools,the bottom water coning in these oil pools results in some difficulties for extraction.Therefore,in order to suppress this kind of phe- nomenon in the bottom water pool,petroleum engineers have acquired some methods to suppress the coning of bottom wa- ter.The off-taken potential of well pattern in bottom water pool of horizontal well is derived from the principle of image method,and the parameter optimization of the length of hor- izontal well is discussed.It can be concluded that the off- taken capacity and the time of water breakthrough of hori- zontal well are subject to the length and position of horizon- tal well,and the anisotropy of oil pay.