Abstract: Fault model is the basis of fault-tolerant research on network on chip (NoC) .Since the conventional fine-grained fault model could not distinguish link failures from channel failures effectively, a finer grained fault model, which is named very fine-grained fault model, is established in this paper to further improve the utilization rate of NoC resources, and a fault-tolerant routing algorithm based on buffer reuse of faulty links (FRA-BRFL) is also proposed.The algorithm adds 4 self-communicating channels (SCC) for each router, and adopts transparent transmission mechanism based on buffer reuse (TTBR) .Reusing normal buffers and channels at both ends of the faulty link to transmit packets of faulty channels transparently, TTBR can increase the probability of packets outputting with optimal port.The experimental results demonstrate that, FRA-BRFL has obvious advantages in NoC with high failure rate, and the algorithm can perform better in average throughput, average latency and average hop counts with lower hardware overheads.