Abstract: Cellulose and chitosan are the two most abundant natural biomass polymers on the earth. The novel, green and functional composite nanofibers derived from cellulose and chitosan were expected to be obtained by electrospinning, which can further expand their applications. The selection and development of the optimum solvent system is a crucial prerequisite and guarantee for the preparation of high-quality nanofibers by electrospinning. The characteristics, dissolution effects, mechanisms and spinning performance of the main solvent systems(including organic solvents, aqueous solvents and ionic liquid solvents) for electrospun cellulose, chitosan single and composite nanofibers were reviewed, which could provide a theoretical reference for the high value-added nano-utilization of cellulose and chitosan as well as the development of functional biocomposite nanofibers.