SoC design is based on Bus Structure. It can resolve the complex system and multi-processor system effectively. NoC applies the computer network technology on system structure, and it will deal with the complex SoC design. The paper presents a new Chip-Only-Writing Bus (COWB) for the communication among the NoC resources. We define the communication protocol and data frame format for COWB. Utilizing MicroBlaze processor as the main resource, DDR2 controller and RS232 controller as the slave resources, the reliability of the COWB is verified with the Xilinx XUPV5 FPGA platform. The testing results show that COWB is easy to expand the number of slave resources and the main resource will access two slave resources simultaneously.