Abstract: The basic structure of variable universe fuzzy controller is expatiated firstly.Under the condition of tacit information,a method is presented,i.e.,the peak-value-points of membership functions on the antecedent parts of inference are placed equidistantly,and the similar points on the consequent parts of inference are regarded as undetermined parameters.The recursive least square algorithm serves as a fulfillment algorithm,and the ending condition of this algorithm is discussed.Simulation experiment shows that a controller designed by the algorithm can approximate original input/output data with fine effect.