A solid electrolyte contains an internal component and an external component coated on a surface of the internal component. The internal component is represented by a formula Li1+xMxZr2−x(PO4)3, M is one or more elements selected from a group consisting of Al, La, Cr, Ga, Y, and In, and 0.05≦x≦0.4. The external component contains a plastic deformable material and has a conductivity of about 10−7 S/cm to about 10−5S/cm. A method of preparing the solid electrolyte and a lithium ion battery including the solid electrolyte are also provided.