The subject discussed in this paper is the rectangular plate. Its two opposite edges are simply supported, while the other two are arbitrary, and the rigidity of the plate is. variable along the direction parallel to the simply supported edges. In order to solve the problem, the author adopts the finite plate-strip element method, which is different from the usual finite element method or the finite strip method. The steps of the above method is no longer to establish a rigidity matrix for elements or strips and gather them into a total matrix for solution. Now the relation of transfer between the strain and inner force of every plate-strip is shown.Finally a practical example is given and this method is found to be easier and more effective.