Abstract: A reinforced concrete base plate supporting the column of the lowest basement of buildings is studied as an orthotropic plate on elastic foundation with four edges free and subjected to a concentrated load at the center. To obtain the bending moment at the center of the plate, the concentrated load must be transformed into distributed load acting on an area equal to the cross sectional area of the column. A general analytical solution for bending problem of orthotropic rectangular thin plates on double-parametric elastic foundation is established in this paper, which can be used to solve precisely bending problems of rectangular plates subjected to arbitrary loads and arbitrary boundaries. For the purpose of illustration, a square plate with four edges free and uniformly loaded on a small area near the center is analyzed and the maximum bending moment is obtained. This general solution can also be applied in the analysis of single-parametric elastic foundation and isotropic plates.