This paper presents the current study of using a constraint based approach to solve floor layout problems. Nonlinear programming technique is used for the solution searching. This paper presents the authors'attempt to improve the nonlinear programming techniques for floor layout problems. Unlike most nonlinear programming systems, multiple optimized solutions can be provided with this system. The process of solving a layout problem, from constraint specification to solution searching, is described in detail. A case study is given in the last section before the conclusions to illustrate how the proposed model works.