Currently, most of Network on-Chip (NoC) architectures have some limitation in routing decisions. And it makes router nodes overloaded, and sequentially forms deadlock, livelock and congestion. A simple unbuffered router microarchitecture for S-mesh NoC architecture is proposed in this paper. Unbuffered router transforms message without making routing decision. Simulation results showed that S-mesh could get optimal performance in message latency compared with 2D-mesh, Butterfly and Octagon NoC architectures. The Design Compiler synthesis results showed that unbuffered router has obvious advantages on area, and it gets higher operation speed.