Thinking through visual design and images plays always an important role in creative activities. In literature, a gift of visual thinking is sometimes identified with the name “autism” and “autistic perception of external world” [www.grandin.com/inc/visual.thinking.html 2000]. Yet, a nature of autism is not well understood. It is evident only the fact that visualization skills enable designers to build products images by taking small parts of these images in their imagination and coupling them together. To create new designs they use visual memory for retrieval of the most essential pieces and combining them into a new whole. Today we cannot mention any computer model of conceptual design, where properties of visual thinking have been somehow realised. In fact, we deal with developing models of verbal thinking in symbols and words. In this sense, basic design images are not considered as mental pictures, but rather as single design concepts concerned with specification of certain design components. For this reason, an attempt is made in the present paper to propose a more adequate approach to modelling a visual thinking in design. The main feature is the development of cognitive structures for representation of visual images in the form of so called compositional design aggregates. It is also studied what reasoning procedures should be used for coupling these aggregates. Finally, application problems of visual thinking with respect to the collaborative web conceptual design are discussed.