Masonry load bearing wall subjected to vertical concentric and eccentric loading may collapse through instability. The buckling behavior of masonry load bearing wall of different slenderness ratio were investigated via testing a series of scale masonry wall subjected to concentric and eccentric vertical loading. A total of thirty six masonry walls were tested in the Laboratory of Technical University of Catalonia (UPC), which was the basis of this numerical study, and results such as the vertical load capacity, vertical deformation, horizontal deflection and type of failure were investigated. In this research, for better understanding of buckling failure of the masonry load bearing wall and to simulate the response of walls tested in laboratory, a numerical finite element model was developed based on the simplified micro model approach. The numerical model was calibrated by using those results found from experimental study. The numerical model was developed, which takes into account both geometrical and material nonlinearities. However, a series of analytical studies were conducted in order to access the accuracy and performance of formulations provided by EUROCODE 6 and ACI-530 for vertical capacity of masonry wall. The influence of tensile strength of units, nonlinear behavior of interface element, slenderness ratio and various end conditions have been investigated together with the effect of different end eccentricity of vertical load.