  We present a kind of generalized Vaidya solutions in a generic Lovelock
gravity. This solution generalizes the simple case in Gauss-Bonnet gravity
reported recently by some authors. We study the thermodynamics of apparent
horizon in this generalized Vaidya spacetime. Treating those terms except for
the Einstein tensor as an effective energy-momentum tensor in the gravitational
field equations, and using the unified first law in Einstein gravity theory, we
obtain an entropy expression for the apparent horizon. We also obtain an energy
expression of this spacetime, which coincides with the generalized Misner-Sharp
energy proposed by Maeda and Nozawa in Lovelock gravity.
