The invention discloses a polythioether imide and polyarylene sulfide alloy material and a preparation method thereof, and the alloy material comprises the following raw materials by weight: 8%-95% of polythioether imide, 4%-9% of polyarylene sulfide, 0.01%-1% of antioxidants, and 0.01%-1% of other additives. The preparation method comprises the following steps: well mixing the raw materials, adding the raw materials into a twin screw extruder, controlling the temperature to 290-380 DEG C, performing extrusion and granulation to obtain the polythioether imide / polyarylene sulfide alloy. The preparation method of the invention prepares a polythioether imide and polyarylene sulfide alloy material with excellent comprehensive properties by a melt blending method; the alloy material has good hear resistance and shock resistance; the disadvantages of poor processing formability, alkaline corrosion intolerance, high price of polythioether imide, and poor shock resistance of polyarylene sulfide are greatly improved; and the preparation process is simple.