Abstract: To study the rate of energy and momentum loss of a heavy quark in QGP, specifically in the hydrodynamic regime, we use fluid/gravity duality and construct a perturbative procedure to solve the dual string in gravity side. We show that the world-sheet horizon and thereby drag force exerted on the quark can be computed perturbatively, order by order in a boundary derivative expansion. We apply this procedure to a quark moving in Bjorken-flow and compute drag force exerted on the quark up to the viscous order. At the ideal order, we find that drag force is localized version of drag force related to a quark moving in thermal plasma while at the viscous order, derivative corrections appear.