By analyzing the Grid characteristics and referring to the trust relationship of social people

this paper proposes a trust evaluation model that is based on Dempster-Shafer evidence theory.This model introduces the "direct trust" according to the trade records.The "indirect trust" is presented by combining the recommendation evidences

while the "combined trust" is proposed by combining the direct and indirect trust

so as to implement the complete fusion of all trust information.The application case efficiently proves the trust model proposed is feasible and practical.