Abstarct: For iran's pavilion desining in Milan Expo 2015 with (Feeding planet) and (Energy for Life) theme, approach which should be followed in order to respond to international concerns arising from the energy crisis. To achieve this goal, Biomimetic approach to achieve this goal, Biomimetic approach was chosen as a main component for emulating nature to solve the technical problems, the coexistence and harmony with nature. In Architecture, The external shell has the most interaction with environmental factors in addition to the aesthetic aspect, can be inspired by the natural organism - which is baxsed on the theory of evolution in nature have adapted over many years - to find an option to answer Milan expo's theme. In this thesis, the method of parametric design and evolutionary architecture using software that was used to simulate the environmental conditions and design trend has continued.by genetic optimization and analysis and feedback on initial ideas. To achieve this, the drought-resistant plants, their permanent presence in difficult environmental conditions and adapt with it is examined and the cactus with their "self shading" properties as the original idea was studied. And eventually became associated with ideas of nature, and material selection.Expo and it's aims to how countries will face with that is investigated and because the country's introducing their identity and cultural to the world the same as horizonsindustrial and technological advances .Therefore to show Iranian culture and architecture identity, patterns were studied for Iran to respond to the Expo goals.In the cultural field, reflects the hospitality of Iranian architecture were studied and in traditions of Iran glaciers in the climate model and its results was reflected in the architectural design.In simpler terms the plan formation process can be summarized in three steps:In the first step the basic idea of using nature-inspired patterns. In the second step, climatic and social mechanisms in traditional Iranian architecture were used .In the final step, this study was conducted by simulating the design process using a method baxsed on current nature as Biomimetic.