Abstract: Based on the following assumptions: a well near the oil water contact with constant pressure and straight-line edge is produced with constant flow rate,the oil of the layer with homogeneity in horizontal direction is radial flowed,the paper derivate the equation of motion of edge water. The time of the breakthrough of edge water and that of bottom water are analyzed and compared with. These are important and positive meaning to instruct to analyzed producing water of a well and to drill infill wells to exploit remaining oil.