The invention discloses a method for cleaning the surface of a magnesium aluminum alloy subjected to chemically mechanical polishing, aiming at providing a simple and easy cleaning method capable of reducing the subsequent processing cost of the alkali chemically mechanical polishing of the magnesium aluminum alloy and improving the surface quality of a wafer. The method comprises the steps of: taking ultrapure water with resistance of above 18M omega, stirring and adding a non-ionic surface active agent and an FA/O chelating agent at the same time; adopting an ultrapure water diluting rust inhibitor with resistance of above 18M omega; adding the diluted rust inhibitor into the liquid under the stirring, uniformly stirring to obtain a soluble surface cleaning liquid, rapidly carrying out polishing cleaning on the magnesium aluminum alloy subjected to the chemically mechanical polishing by using the obtained soluble surface cleaning liquid under the condition of large flow and low pressure; and washing by using the ultrapure water with resistance of above 18 M omega under the condition of zero-pressure and large-flow.