Abstract: Synthetic ionospheric sounding system,including a number of different subsystems,which performance can be effectively improved by transmitting perfect orthogonal signals.The complete complementary sequence(CCS)is composed of several complementary orthogonal sequences.Based on it,waveform of synthetic ionospheric sounding system transmitting signals is proposed.The way of CCS construction is described and the performance of CCS is studied,The results of computer simulation show that CCS is satisfied with the requirement of the orthogonal signals. The application of CCS in synthetic ionospheric sounding system is studied and the system model based on CCS is established.The results prove the rationality of CCS applied in synthesis ionospheric sounding system.