In this paper, a scheme for digital secure communications is proposed by using different drive functions of hyperchaotic systems based on APD approach. Two different drive functions can be alternately sent according to the transmission of binary signal “0" and “1", which will enhance the complexity and decrease the correlation of transmitted signals. Meanwhile, by designing compound nonlinear function transformation for transmitted signals to further intercalate the secret key, a determined intruder is very difficult to retrieve the contents of message signal using forecasting method. Theoretical analysis and numerical simulation results show that this method is effective.