Non-linearity in structural Analysis is caused in most cases by two factors ; one is plastification of material and another is finite deformation. These two factors usually make the analysis so complicated that it is difficult to obtain the exact analytical solutions. Therefore, numerical analysis is used to get approximate solutions. In this paper, as a first step for solving square plates subject to lateral pressure, one approximate numerical procedure is used for solving the same kind of problem of strip plates. This procedure is based on linearization of non-linear equations by the concept of small increment and on solving these linearized equations by finite difference method. From the fact that analysis of strip plates can be regarded with good accuracy as the analysis of square plates subject to lateral pressure, provided that their aspect ratios are over about 3, the strip plates have been investigated by several researchers analytically and experimentally. The comparison showed that the computed load-deflection curve by the procedure in this paper coincided with the experimental ones published previously with fairly good accuracy. Another results of this paper is estimation of the effect of end restraints of strip plates. The behaviour of strip plates with linear and non-linear end restraints were investigated.