In order to solve the problems of stability and durability of red clay subgrade under the action of humidification, it was proposed to add construction waste into red clay for physical improvement, and the basic physical performance properties of mixed samples under different incorporation ratios of construction waste were tested. Then, the coupling influence of construction waste incorporation rate and initial moisture content on the mechanical properties of mixed samples were qualitatively and quantitatively evaluated by means of the resilient modulus test, failure strength test and permanent deformation test. The results show that when the incorporation rate of construction waste was the same, the resilient modulus and failure strength decreased with the increase of initial moisture content, while the permanent deformation value increased with the increase of initial moisture content. When the initial moisture content was the same, the resilient modulus and failure strength firstly increased and then decreased with the increase of construction waste incorporation ratios, and the value would reached its maximum value at 10 percent incorporation rate. The permanent deformation value firstly decreased and then increased with the increase of construction waste incorporation ratios, and the value would reached its minimum value at 10 percent incorporation ratios. Based on the experimental results, the prediction model of permanent deformation was established to provide a useful reference for the practical application in red clay subgrade modified by construction waste.