Abstract: Int his paper, a finite element method of triongular division is presented for a two dimensional-and two phase (oil and water) nonlinear model in reservoir.Authors designed associated computer program, gave the saturation distribution during oil production with the data in Daqing oil field in connetion with IBM-PC/XT computer, and predicted the break through time with satisfactory results.On the basis of theoretical analysis and the results the finite element method was compared with the finite elent method of rectangular division and the finite difference method.