Agricultural waste of corn straw pulp was successfully prepared into fibers using a tetrabutylammonium acetate (TBAA) and dimethyl sulfoxide (DMSO) solvent system via a dry-jet wet spinning process at 35 °C. The dissolving process of cellulose in TBAA/DMSO was observed through a polarization microscope, and the rheological behavior of the cellulose/ TBAA/DMSO solution was also studied. The crystalline and microstructure of the regenerated cellulose fibers prepared from corn straw were investigated by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). In addition, the morphology was characterized with a scanning electron microscope (SEM). The thermal stability of corn straw pulp and the regenerated cellulose was also explored. Due to the presence of residual lignin, a longer time was needed for the complete dissolution of corn straw compared with pure wood pulp. In addition, the degree of polymerization and the elongation-at-break of the regenerated fiber had a small amount of attenuation. Despite the deficiencies, a good spinnability of corn straw cellulose solution could still be achieved. Fibers with a round and compact structure as well as a smooth surface were obtained.