Traffic engineering based on SDN (software defined network) can select routing paths dynamically in order to evade the risk of congestion through global view of network in data centers. However, the design of routing strategy often needs to change routing path during packet transmission, especially for elephant flows, which may commonly result in the problem of packet losses and out-of-order at receivers. To address the problem, an algorithm named "flowlet-binned algorithm based on timeslot (FLAT)" is proposed. FLAT is able to gather the information of link state and calculate the proper transmission timeslot under centralized control, which can solve the problem of packet losses and out-of-order. In the meantime, traffic balance with high efficiency and fine granularity can be achieved under considerable use of the redundant links in data centers. Finally, simulation results show better performance of FLAT in Mininet platform compared with ECMP and GFF routing strategies with the packet loss rate respectively falling by 90% and 80%, and the throughput increasing by 44% and 11%, especially under the condition of high load of links.