In order to establish trust relationship between service requesters and providers in an open decentralized environment, we propose a novel trust negotiation framework, TOWER, which integrates distributed trust chain construction of trust management and aims to enhance the grid security infrastructure. Our approach leverages attribute-based credentials to support flexible delegation, and dynamically constructs trust chains. A novel TRust chAin based Negotiation Strategy (TRANS) is proposed to establish trust relationship on the fly by gradually disclosing credentials according to various access control policies. Our approach has been successfully implemented as useful components and fundamental security services in the CROWN Grid, and techniques such as trust tickets and policy caching that can greatly increase service efficiency are used. Finally, we evaluate our approach by comprehensive experiments and the results show that it is feasible.