In Vtr layout procedure, Steiner tree is often applied to implement tile global routing, and it can be also used to do the detailed relating when considering the obstructs between sub-circuit unit or models. This payer proposes the concept of float pin to construct Steiner tree. With the development of IC technology, timing problem becomes more and more important, Applying Elmore delay model and taking the multi-layer muting into account, we give out an algorithm TAFLOST of constructing float pin timing-driven Steiner tree.