The concept of free-form interior design as a modern trend is A topic worth to study. That recently designers have an attempt to get out of the concept of the inner cubic space, which depends in its design on geometric shapes and sharp lines, to a space outside the box that depends in its design on imagination and free vision. Free form using the irregular lines and the curves lines to create a new language in design by new formations that are not belongs to the recognized standard rules of design. This change in the form of the inner void has a different and perceptible impact on the users' psychology and visual perception. Within the diverse spaces, the form may conflict with the void function requirements. So, the paper discusses the relationship of the free form with the function of interior spaces by analyzing and criticizing diverse examples of the interior spaces designed with free formation to verify its impact on the reaction or response of users.