The effect of electron-electron interaction on the localization of soliton is studied. Because the conducting polymer possesses wide bandwidth, the Hubbard model is no longer a suitable approximation. It is needed to use a screened Coulomb potential to describe the e-e interaction. Our theory shows that the screening plays a key role in the effect of e-e interaction on the localization of soliton: in weak screening, the localization of soliton will be enhanced by the e-e interaction; in strong screening, it will be reduced. In the end, the physical reason of above-mentioned results is explained by analysing the relation between screening and electron correlation.