Based on the indepth study of IEEE1149.7 standard, the paper designs and implements the target chip CJTAG IP core in the test architecture proposed by standard to solve the problem of test. The design and implementation of reset and selection unit （RSU）module is mainly introduced. The RSU module mainly realizes four functions: Startup options choice, reset signals generation, escape detection, RSU online/offline choice. The design is based on the Quartus II application platform and through the ModelSim to complete the simulation and verification. The simulation results show that the test signals generated by the RSU module can meet the requirements of IEEE1149.7, and can be able to achieve the appropriate test function of the CJTAG chip.