Washburn method was applied to investigate on the wettability of the organic bentonite modified by molecular deposition filming flooding agent (MDFFA) mixed with tetraethyl ammonium bromide ［(Et) ₄NB］, dodecyl trimethyl ammonium bromide (DTAB) or hexadecyl trimethyl ammonium bromide (CTAB). The results show that the organic bentonite absorbed MDFFA is more hydrophilic than that of organic bentonite absorbed (Et) ₄NB,DTAB,CTAB, then the oil wettability of organic bentonite absorbed MDFFA is lower than others. For the solution of MDFFA mixed with (Et) ₄NB,DTAB or CTAB, with the increase of MDFFA volume proportion the organic bentonite is more hydrophilic and the oil wettability is lower, especially for the organic bentonite treated by the solution of MDFFA mixed with (Et) ₄NB, when (Et) ₄NB mixed with a little MDFFA the organic bentonite is more hydrophilic than that of absorbed (Et) ₄NB and the oil wettability is lower obviously.