Fault-tolerant topology control is a critical problem in WSNs. It is important for improving network lifetime and reliability. In this paper, we present a novel algorithm FTMRT, which ensures Fault Tolerance by constructing a Multi-Routing Tree. We firstly construct a multi-routing tree of the initial topology, which ensures there are at least k-disjoint paths from each sensor to the set of supernodes. And then each sensor adjusts its transmission power according to the multi-routing tree to form the fault-tolerant network topology. In the topology maintenance phase, topology reconstruction is invoked each time there are some node fail and the supernode connectivity is broken. The effectiveness of the proposed algorithm is validated through simulation experiments.