<p>This study investigates the thermosolutal convection of a power-law fluid with variable gravity in a vertical through flow that is heated and salted from below. Linear instability analysis investigates the growth of small disturbances in a system. After non-dimensionalizing the governing equations, they are linearized around a base state. The normal mode method applied for solving the perturbation equations. It gives the exponential form to solve stability criteria. The complete study was analyzed by using linear stability analysis; the influence of variable gravity is studied. This theoretical study investigates double-diffusive convection within a porous media filled by power-law fluid. It mainly examines how gravity and concentration gradients influence on thermal solutal convection behavior. The focus is on vertical through flow and its role in the onset and effect of instability.</p>