Negative dielectric constant in gold nanoshells thin film has been investigated by means of Maxwell-Gamett (MG) effective medium model and quasi-static theory. Numerical calculation results show that the real part of average dielectric constant may change from negative, through zero to positive values near the resonance wavelength. The negative band width can be tuned by changing the local environment dielectric or gold shell thickness. The surrounding dielectric constant and thin shell thickness have greater capability to alter the negative wavelength range. (C) 2009 Elsevier B.V. All rights reserved.