An optical fiber with anisotropy metamaterials in the core and a common medium in the cladding is investigated. Firstly, four dispersion equations for the oscillating guided modes based on Maxwell′s equations are obtained. From the dispersion equations, and considering frequency dispersion of practical metamaterials, some dispersion curves for TE、TM、HE and EH modes are plotted. Some new dispersion properties of the oscillating guided modes are gotten by analyzing and comparing these curves, such as: the effective-refractive index increases individual with the frequency; as frequency adds, TM oscillating guided modes have a fixed velocity and EH modes always have two different group velocities and mutation frequency is 4.46 GHz. Besides, as mode number increases, the dispersive curves move along up and left direction; however, as the core radius increases, the curves turn along down and right direction and the bandwidth of HE11 oscillating guided mode becomes widely. In all words, these are interesting dispersion properties and may make a direction to design high quality fiber.