Composite stiffened panels have been used in aerospace industries for past decades. Due to light weight nature composite panels are prone to buckling. In this study buckling load for Ortho-grid panel and Iso-grid panel is determined. This was accomplished by developing a composite laminate for both skin and stiffener using MSC PATRAN/NASTRAN was used for linear buckling analysis of composite panels. The buckling loads of two panels were determined based on finite element analysis results, including geometric dimension, thickness of the skin, number of laminae, ply stacking sequence, thickness and height of stiffener. Parametric studies of general grid stiffened panel was conducted using skin thickness, stiffener thickness and stiffener height as design variables. Conclusions drawn from these results are presented. All three buckling modes appeared and maximum buckling load was observed in skin buckling mode for Iso-grid panel.