Consider several unknown non-linear functions, which are approximated respectively by several known fuzzy logic systems (FLSs) with fuzzy if-then rules which may be proposed by several experts based on intuitiveness or the heuristic estimation from sample data. This paper discusses the problem for how to use the several known fuzzy logic systems to generate a new fuzzy logic system which can be utilized to construct a new approximate model for a new nonlinear function composed of the several unknown nonlinear functions. The example shows the validity of the methods in this paper.