In the paper the idea of expert aided control design is illustrated for the case of pressure - level pilot plant. It has been built for control studying purposes as this type of variables can frequently be met in process industry. First some basic expert system principles are formulated, for which we believe, can be very valuable for the users. This ideas are further connected with the combination of classical design and neural network approach used in the role of controllers. Finally the synthesis procedure for the discussed plant is described and proved with some results. At the end of the paper the ideas for further work are indicated.