The invention discloses a mechanical polishing solution for preparing an EBSD sample, a preparation method and a mechanical polishing method, and belongs to the technical field of Ni-base single crystal superalloy crystal orientation analysis. The mechanical polishing method of the Ni-base single crystal superalloy EBSD sample is provided for solving the problems that the Ni-base single crystal superalloy EBSD sample is complex in preparation process, time-consuming, low in indexing rate and the like, and the mechanical polishing method with easy preparation of the polishing solution is easy and convenient to operate, low in cost, good in polishing effect and high in indexing rate. The polishing solution is composed of 25 wt%-30 wt% of colloidal silicon dioxide, 2 wt%-3 wt% of hydrogen peroxide, 1 wt%-2 wt% of oxalic acid, 2 wt%-3 wt% of glycerinum, and the balance a pH modifier and distilled water. The mechanical polishing method comprises the steps of (1) cutting, (2) cleaning, (3) inserting, (4) grinding and (5) mechanical polishing. The mechanical polishing method is easy to implement, low in energy consumption and suitable for preparation of the Ni-base single crystal superalloy EBSD sample.