In this paper, supposing that the following equation is concluded, it induces the model of a field lot as a unit in the case of thinking about percolation on large project, and moreover we discuss about some quantities measured in practice. ∂x/∂（R2/1 ∂ｘ/∂H)＋∂y/∂(R2/1 ∂ｙ/∂Ｈ)＋R1/1（H0-H)=0 The results in this paper are summarized as follows. l) In treatment of percolation in the paddy field on large project, the unit is one field lot surrounded with drainage canal. Regarding the one field lot as a unit, physical quantities concerned are q , q1, q2, S1 and S2. We induced the relation among them. 2) Thinking" about the vertical section crossing drainage canal in the two dimension, the apparent model indicating" the motion of percolation water in that vertical section is shown in the Fig. 2, and moreover it is transformed to equivalent model shown in the Fig. 4. Parameters indicating the characters of this model are R and RH, or R' and RH'. 3) This model is induced from the start-point of equation (1) concluded in the macro soil model. And then, in the two layer geometrical model L/D=5, D/d=4, as the result of comparing Darcy's dimensional solution with this model in the case of k2/k1=1 and k2/kl=20, both are not very good consistent in the case of k2/k1=1, but are fairly good consistent in the case of k2/k1 = 20. From this result, it may be considered that the propriety of applicable extent (k2/k1 > 10) for the macro model could be proved. 4) The quantities measured in practice are q , S . S1 and S2, and parameters included in the equations should be calculated back from these quantities.