The invention provides a method for determining the optimum water content and the maximum dry density of cement-stabilized macadam. The method includes the steps that firstly, a compaction test of the cement-stabilized macadam under the cement dose a is conducted, and the maximum dry density rhoa and the optimum water content omegaa are obtained; secondly, the optimum water content omegab and the maximum dry density rhob under the cement dose b are calculated, wherein omegab=omegaa+m(b-a), another formula is shown in the description, m is the optimum water-cement ratio under the cement dose a, ic is the mixture hydration increment percent under the cement dose a, and rhocr is the cement density. By means of the method for determining the optimum water content and the maximum dry density of the cement-stabilized macadam, the workload of the compaction test of the cement-stabilized macadam material can be reduced, the test cycle can be shortened, and meanwhile the accuracy of the optimum water content and the maximum dry density can be guaranteed.