Based on averaged cyclic periodogram cyclic spectral density estimating method(ACP), the cyclic spectral features of complex modulated signals are studied and the correspondence with signal parameters is investigated. The feature extraction methods without prior knowledge are developed. Firstly, the expression of complex modulated signals is described and the relationship between signal parameters is given; Secondly, the cyclic spectral features of signals are analyzed using ACP cyclic spectral density estimating method, the features correspondence with signal parameters is obtained; Based on the above, a method for parameter extracting based on cyclic spectral features is proposed. The normalized RMS error (NRMSE) of frank coded and Costas coded signals parameter extraction are measured to verify the validity of the method.