The invention provides a flexible solid-state lithium ion conductor and a preparation method thereof, belonging to the technical field of energy storage and conversion materials. The flexible lithiumion conductor comprises at least two components containing lithium ions, wherein one component is an inorganic or organic lithium salt, and the other component is a polymer; and the main chain of thepolymer has at least one of an ether oxygen bond, a carbon nitrogen single bond, a carbon oxygen double bond or a silicon oxygen bond, and contains lithium ions coordinated by ionic bonds. The solid-state lithium ion conductor provided by the invention is a flexible body with plasticity, the room temperature ionic conductivity is greater than 10<-4> S/cm, and the lithium ion migration number is greater than 0.4. The flexible solid-state state lithium ion conductor provided by the invention is applied to a solid-state battery including a lithium ion battery, a metal lithium battery, a lithium sulfur battery and a lithium air battery; the flexible solid-state state lithium ion conductor provided by the invention can be introduced as an adhesive into an electrode or as a solid-state electrolyte at the same time due to the high lithium ion conductivity, high tensile strength and certain plastic deformation ability, which exhibits excellent interface stability and cycle life.