Abstract: Morphiceptin (Tyr¹-Pro²-Phe³-Pro⁴-NH₂) is an endopeptide just as enkephalin and β-casomorphine. Morphiceptine displays high selectivity to μ-receptor. Most of the spatial characters of the bioactive conformation have been elucidated by ¹H and ¹³CNMR spectroscopy in recent years. However, theoretical research of this peptide has not kept up with experimental studies. In this paper,molecular dynamic simulation and systematic conformation search for this peptide have been performed. We intended to explore a set of low energy conformations . Our computational results have shown that our theoretical method in finding the preferential conformations is very efficient. Comparison of the electronic characters between morphiceptin and morphine after optimization using AM1 parameterization has been made. The comparative results have manifested that morphiceptin and morphine are very similar in both spatial arrangement and electronic characters.