The invention discloses a method for preparing a high-porosity ceramic cement grinding wheel for polishing silicon single crystal rods, which comprises the following steps of: cutting a sponge board according to the required grinding wheel specification, and cleaning and drying for later use; uniformly mixing a diamond abrasive, boron glass powder, feldspar powder and quartz powder in a certain mass ratio under the condition of ball milling, and preparing ceramic slurry with water glass solution in a proportion; putting the sponge board into a sealed container, vacuumizing, introducing the ceramic slurry into the container by using a guide tube for immersing the sponge board, and keeping the pressure; taking the sponge board immersed with the ceramic slurry, drying, wiping off surplus slurry on the surface, and drying again; repeatedly immersing and drying twice; drying the sponge board completely immersed with the slurry at 80 DEG C for 24 hours in a drying oven, putting into a pit furnace, completely burying by using white corundum, sintering under the protection of N2, keeping 700 DEG C for 1 hour, and cooling with the furnace; and processing the excircle, inner circle and plane of the sintered grinding wheel blank. Through the method, the diamond grinding wheel having a consistent structure and the porosity of more than 60 percent can be prepared.