In the paper, associative search identification models in variable structure control systems are considered. The methods of non-linear systems identification by using the multiple-scale wavelet transform are presented. A methodology of a variable structure control system’s synthesis is presented based on information models. Issues of the stability of a model built by use of the associative search are considered, in the aspect of the spectrum analysis of the multi-scale wavelet expansion. Methods based on the wavelet analysis are characterized with a unique possibility to select ''frequency-domain windows''.