Abstract: The back flow effect of ooze-rock in toe-shooting method was analyzed. It concluded that the viscidity of ooze is a drag of motion of the ooze-rock all along; when the ratio of gravity to viscous resistance is over 150, i.e. the (ppp)r>150, the influences of viscidity of ooze and initial fill form of the ooze-rock can be all neglected in the back flow of the ooze-rock.