Abstract:  The covert performance of direct－sequence spread－spectrum(DSSS)communication under the condition of the log－normal fading underwater acoustic channel was investigated in this paper.Firstly，the model of covert underwater acoustic communication system was established，the interception factor based on the detectable acoustic communication distance was proposed as the method to measure the covert performance of the underwater acoustic communication system.When the DSSS communication signal was transmitted through the log－normal fading underwater acoustic communication channel，the receiver operating characteristic(ROC)of the energy intercepted receiver was investigated theoretically，as well as the ROC of the synchronization detection and the Bit Error Rate(BER)of the DSSS using the communication receiver.The influences of different underwater acoustic communication channel attenuation parameters，acoustic communication signal parameters and modulation types of the acoustic signal were analyzed theoretically and simulated base on intercept factor.The simulation results show that under the condition of logarithmic normal distribution fading underwater acoustic communication channel，DSSS communication has the low probability of intercepting communication capability；under certain conditions，reducing the emission carrier frequency，increasing time－bandwidth product，reducing the communication modulation order or communication rate of the acoustic communication signal will be beneficial to improve the covert performance of underwater acoustic communication system；shallow sea acoustic communication channel is more conducive to the realization of underwater covert communication than deep sea，as well as the short－distance channel is easier to achieve covert underwater acoustic communication than long－distance underwater acoustic channel.