To improve the reliability and security of underwater acoustic (UWA) FH system, a method producing frequency hopping (FH) pattern is presented based on bit error rates (BER) mapping and the quantification of pseudo random numbers. BER of all FH channels are ma pped into the probability density function (PDF), a quantitative vector can therefore be obtained. Furthermore, the pseudo random numbers, produced by the pseudo random number generator, generate FH patterns according to the specific statistical rule and quantitative criteria, which are used for FH communications. A specific adaptive FH communication simulation system based on probabilities is further established. Experimental simulation demonstrates that the proposed method has a lower BER compared with the traditional FH or adaptive FH. Moreover, it features better security performance.