The invention belongs to the technical field of 
energy storage devices and particularly relates to a high-safety flexible linear 
lithium ion battery and a preparation method thereof. The preparation method comprises the following steps: winding 
lithium manganate nano grains and an irregular multi-wall carbon 
nano tube mixture into an orientated multi-wall carbon 
nano tube thin film to obtain a positive 
electrode composite 
fiber; meanwhile, winding 
lithium titanate nano grains into the other same orientated multi-wall carbon 
nano tube thin film to form a 
fiber; wrapping the surface of the 
fiber with one 
thin layer of 
graphene oxide to obtain a negative 
electrode composite fiber; and finally, packaging the positive 
electrode composite fiber, the negative electrode composite fiber and 
electrolyte into a flexible tube to obtain the linear flexible 
lithium ion battery with high battery performance. According to the battery, an 
electrode material with the high safety is wound into a carbon nano tube bundle with excellent electric and mechanical properties to form a 
flexible fiber electrode; a 
metal wire is replaced so that the flexibility and the safety of a device are greatly improved; meanwhile, the fiber battery is light in 
mass, small in volume and large in capacity; the 
flexible fiber electrode is easy to 
braid and integrate and an important reference method is provided for application of the 
flexible fiber electrode in wearable equipment.