At present，polymer has been used widely in daily life，production，science research，national defense and other fields，and has become a focus area for scientific research. This article mainly discusses the background and significance of the development of polymer，explains what polymer is，what knotted polymer is，and what properties the polymer owns. In this work，we choose polymethylene (PM) chain as the object，use the method of Steered Molecular Dynamics(SMD) to study knotted polymer based on united atom (UA ) model，and obtain the changes of bond length，bond angle，torsion angle and strain energy of the knotted polymer chain during the extension，and then discuss the influence of a knot on the properties of polymer by analyzing the Simulated graphs.
