The invention discloses a preparation method of polyurethane sieve plate. The method comprises the following steps of: (1) preparing a prepolymer; (2) mixing; (3) casting; (4) precuring and demoulding; and (5) post-curing. The method provided by the invention uses polyester and polyether polyol as raw materials, improves abrasion resistance of the product through introducing nanometer barium sulfate powder, reduces flexibility and improves stiffness of an ether bond through introducing aryl with a steric effect into an ether bond-containing chain extender, thereby enhancing stability to hydrolysis resistance and ensuring various physical and mechanical performances of elastomers at the same time.