Monaural speech segregation is a very challenging problem which has been studied by many researchers. In this paper, we focus on voiced speech segregation. Different strategies are used to segregate resolved and unresolved harmonics respectively. For resolved harmonics, "harmonicity" principle and a novel mechanism based on "minimum amplitude" principle are employed. Amplitude modulation rate is extracted by "enhanced" autocorrelation function of envelope to segregate unresolved harmonics which is more robust than previous method. An elaborate rule is also introduced to determine the regions dominated by resolved and by unresolved harmonics. Proposed algorithm is evaluated on Cooke's 100 mixtures and compared with a state-of-the-art algorithm Hu and Wang model. Results show that proposed algorithm is more robust than the Hu and Wang model.