Abstarct: Achieving a defect-free product in mextal forming processes undoubtedly depends on a reliable and attributable formability criterion. The present dissertation deals with drawing out of Forming Limit Diagram (FLD) of aluminum sheet AA6061-O using Digital Image Correlation (DIC) approach. For this purpose, five in-plane tensile tests using Instron tensile machine as more as five out-of-plane stretching tests using hemispherical punch were carried out until necking. Mechanical properties of the raw material were obtained by performing proper tests. Calibration of effective DIC variables including: subset radius, subset spacing and strain radius was done to gain the optimal values. To verify the accuracy of the results, in uniaxial tensile test according to ASTM-E8 standard, two faces of samples were meshed using a regular pattern of circles and irregular sprayed pattern. Anisotropy values in directions 0°, 45° and 90° degrees respect to the rolling direction, measured and analyzed using traditional methods (ASTM E517), DIC (regular pattern) and DIC (irregular pattern). Using these values, experimental yield surfaces were drawn for different strains and the plastic hardening of the sheet was obtained for different loading paths. By representing the components of strain and strain rate in terms of process time, different criteria for onset of necking were investigated. Finally, the moving of strain ratio (the ratio of minor to major strain) in to the zero on the necking band was selected as a strain bifurcation criterion. Accordingly by drawing the strain path of each test, limit strains were determined and sheets FLD was drawn. Furthermore, by using the current limit strains and associated flow rule of Hill-48 yield criterion, limit stresses were calculated and Stress Forming Limit Diagram (SFLD) was drawn. Finite element simulation was applied to design the die components and evaluate the results of experimental strain passes and FLD. Representing the related strain path on the experimental FLD of sheet mextals is one of the main innovations of this study, which is important because of the unavoidable dependency of FLD to loading history.