The invention provides a pectin fiber and a preparation method thereof, belongs to the field of macromolecular fiber, and is used for solving the problem that the PEO content in a conventional pectin and PEO mixed fiber is too high. The pectin fiber comprises the components by the mass percentage: 80%-100% of pectin, and 0-20% of polyethylene oxide. The invention also provides the preparation method of the pectin fiber. The method comprises the steps: firstly, mixing a pectin aqueous solution and a polyethylene oxide aqueous solution, then adding a surfactant and a cosolvent, to obtain a mixed solution, and spinning the mixed solution, to obtain an electrospinned nanofiber; and then dissolving the obtained electrospinned nanofiber in a selective solvent, washing, and thus obtaining the pectin fiber. The content of polyethylene oxide in the pectin fiber is lower than 20%, and the pectin fiber has excellent biocompatibility and mechanical properties.