The invention relates to the field of building materials, in particular to a titanium gypsum-based semi-rigid base material and a preparation method thereof, comprising the following components: original titanium gypsum, cement, fly ash, mineral powder, recycled aggregate, water, and an excitation activator , viscosity reducing dispersant; wherein the excitation activator includes the following components: quicklime, calcium acrylate, magnesium fluorosilicate, alunite, sodium tripolyphosphate, potassium sulfate, sodium metaaluminate, and the viscosity reducing dispersant is grafted cis-butyl Polytetrafluoroethylene of olefinic anhydride. The semi-rigid base material of the present invention meets the strength requirements of the road pavement base, and the original titanium gypsum is added in a large amount, which can consume a large amount of the original titanium gypsum and reduce pollution, and the industrial by-product titanium gypsum is added in its original state without drying, calcination, dehydration and powder. Grinding and other processes also protect ecological resources and have a wide range of social benefits, obvious economic benefits, and ecological and environmental benefits.