Using chitosan (CTS) as a model polymer, the feasibility of obtaining aligned ultrafine CTS fibers were demonstrated by employing a small amount of ultrahigh molecular weight poly(ethylene oxide) (PEO) to formulate the solution visco elasticity,which enables to suppress the electrospinning bending instability to form a pretty long and stable jet (this approach was termed as "stable jet electrospinning", SJES). This makes continuous fabrication of aligned ultrafine fibers, as achievable in those traditional fiber forming methods (e.g., dry spinning or dry-wet spinning),to come into reality. Here, a systematical parameter study is reported on the SJES process including mass ratio of CTS/PEO, applied voltage, collecting distance, coagulation bath and rotating speed of drum. Characterization of the resultant electrospun CTS fibers by SEM, FTIR,WAXD and nano-tensile testing was also performed. The result showed that SJES enabled to produce individual CTS fibers with a diameter of <10 mu m. The diameters of CTS fibers 'could be attenuated to ca. 3 pm by varying applied voltage and stretching speed. The electrospun CTS fibers by SJES were of high mechanical performance, with the measured tensile strength and modulus of (762 +/- 93) MPa and (11 +/- 6) GPa, respectively. SJES facilitated polymer chain and crystalline orientation, which may have contributed to the significant improvement in the mechanical properties of thus made ultrafine CTS fibers.