In this work we have investigated buoyancy driven convection in bi-viscous Bingham fluid layer under gravity modulation and its weakly non-linear and linear stability analyses. We derive the critical Rayleigh number expression from linear analysis. From non-linear analysis we compute the heat and mass transport parameters Nu and Sh respectively based on Ginzburg-Landau equation.These numbers are obtained as a function of wavenumber and amplitude of modulation. The Gravity modulation effect on heat and mass transport are obtained in terms of Nusselt number ( Nu) and Sherwood number( Sh) respectively. Further, various parameters have significant effect on heat and mass transport. This is also analysed and depicted graphically.