The investigation of mechanical properties and evolution of nano-porous structure in metallic materials under the complex multi-axial tensile deformation condition have many applications for the design of engineering metallic structures for automobile, aerospace, electronic instruments, etc. In order to understand the stress-strain response and growth-coalescence of nano-pores in aluminium-magnesium (Al + 10 atom%Mg) alloy during multi-axial tensile deformation, classical Molecular Dynamics (MD) simulations were performed. Stress-strain response of aluminium-magnesium alloy exhibit brittle failure during tri-axial tensile deformation. Evolutions of nano-pores have been observed in early stage of plastic deformation of aluminium-magnesium alloy. The Solvent Accessible Surface Area (SASA) and volume of nano-pores (V - V-s) have evaluated for estimation of dimensionless aspect ratio (x) of nano-porous structure of aluminium-magnesium alloy. Our findings will give more insights for better design of nano-porous materials.