The invention relates to a preparation method for a chitosan short fiber reinforced nano stent. The preparation method comprises the following steps: grafting and modifying chitosan short fiber by using a grafting modifying agent; dissolving polylactic acid polymer, adding graft modified chitosan short fiber, freezing the solution under 18 DEG C below zero, and preparing composite gel of the polymer and the chitosan short fiber; displacing the gel by deionized water at 4 DEG C; taking out the gel, and drying after freezing the solution under 18 DEG C below zero again, so as to prepare the chitosan short fiber reinforced nano stent. The prepared three-dimensional grid-shaped stent has a coexistent structure of a nano-scale polylactic acid polymer skeleton, a micron-scale chitosan fiber support and a micron-scale hole which are communicated with each other. Because the chitosan short fiber is added, not only the mechanical strength of a stent material is improved greatly, but also lowering rate of pH value in a degrading process of the stent material is slowed largely. The method is simple and practicable, can control the shape and the size of the stent material randomly according to requirement, and can be widely applied to the field of tissue engineering.