Unsteady simulation of conduction heat transfer has been studied during the solidification of Aluminium casting in green sand mould. Heat conduction equation in two-dimensional governs the physical problem. At the interface where molten metal meets the mould cavity surface convective boundary conditions have been considered. Finite difference analyses (FDA) of heat conduction equation in unsteady state and transient state have been solved using MATLAB R2012a.Central difference scheme for spatial terms and explicit scheme for temporal term have been adopted to discretize the governing equation. Thermal flow and cooling rate have been studied. Green sand mould and pure aluminium has been used as a molten metal and mould cavity material respectively. Temperature distribution of Aluminium liquid metal in green sand mould for two-dimensional casting for steady problem and cooling rate of with time have been plotted.