The invention discloses a sapphire surface treatment technology, and particularly discloses a sapphire polishing solution and a preparation method thereof. The sapphire polishing solution comprises a deionized water solution, silicon dioxide nanoparticles, a dispersing agent, a complexing agent and a pH regulator, and is prepared by the steps of: firstly, adding the dispersing agent and the complexing agent into the deionized water; then, adding the silicon dioxide nanoparticles into the solution, continuously stirring, and simultaneously carrying out ultrasonic treatment for 5-8minutes until the dioxide nanoparticles are completely dispersed; and finally, adding the pH regulator into the mixed solution to adjust the pH value to be 9-11.5. According to the invention, the sapphire polishing solution is directly prepared by the silicon dioxide nanoparticles, so that the prepared polishing solution is low in solid content, effectively saves the preparation time and cost, has the characteristics of high polishing efficiency and long storage time, and is easy for subsequent cleaning technology; less additive which is mostly inorganic additive is used by the invention, so that the sapphire polishing solution is free from harm to the environment and the human body, and has good environmental protection property; and the preparation method is simple, effectivele, very low in requirements and easy to produce.