In many cases we deal with buildings visually from outside, and we may not have the opportunity to test them from the inside, So; many definitions of architecture linked it to the external form of the buildings, Which makes the external shape of the buildings the primary area of judging them regardless of the quality of the internal solution. And this earns the study of the external architectural form importance. The paper discusses the problem of form of building's external envelope in both of the international style architecture and Deconstruction architecture; they were two trends which architectural form was a result of clear and specific theoretical ideas. Despite the obvious differences between the output forms result from the international style and deconstruction architecture; the paper hypothesis that there is some invisible similarities in the way of thinking and the product forms in both trends. The research methodology adopts a critical view by conducting a comparative analysis study for architectural form in both of international style and deconstruction, they are two architectural trends have a clear point of view regarding the architectural form. The study concludes that, despite the obvious differences between the final products of the form of buildings in both trends; but there are some features in common way of thinking. Both trends were thought that form is something that absolutely not related to surrounding context, and it has the priority. Also, the technical development has had a direct impact on the method of producing the form in both trends.