In this article, dynamic analysis of viscoelastic beam, which is made of porous functionally graded materials (FGM), is investigated by using the generalised differential quadrature method (GDQM). The material properties for FG beam are supposed to be graded in the thickness direction by two types of porosities and estimated using a modified power-law form. The surrounding visco-Pasternak foundation is made of viscous layer symbolised by dashpots, parallel springs and a shear layer. The governing equations achieved by Hamilton's principle are solved implementing GDQM. Afterwards, the effects of types of porosity distribution and its pattern, foundation type, power-law index, slenderness ratio, structural damping coefficient and boundary conditions on the damping frequency of the present viscoelastic FG beams are explored.