MoO2@C core shell nanofibers are synthesized via a simple electrospinning method with a single nozzle. The formation mechanism of MoO2@C core shell nanofibers is investigated in detail and it is discovered that the phase-segregation phenomenon may be the main driving force of thermodynamics to form MoO2@C core shell nanofibers, and the high temperature as the dynamic factor can accelerate the formation of these core shell nanofibers. The carbon shell of the MoO2@C core shell nanofibers acts as both conductive bond to increase electrical conductivity and structural skeleton to maintain the integrity of MoO2 during Li+ insertion/extraction to achieve both high specific capacity and good cyclic stability. So as an anode for lithium-ion batteries, the MoO2@C core shell nanofiber electrode exhibits high specific capacity and extraordinary lifetime even at a large current density. Their reversible capacities are 665 mA h g(-1) in the 600th cycle at 0.5 A g(-1). Even at a high current density of 1 A g(-1), a capacity of 537 mA h g(-1) is obtained after 600 cycles. The present work may provide a facile and broadly applicable way for the fabrication and utilization of metal oxide/carbon core shell composites in fields of batteries, catalysts, and fuel cells.