The invention discloses a CuGaS-ZnS core-shell structure quantum-dot material and a preparation method thereof. The material is prepared from a copper-gallium-sulfur quantum-dot core and a zinc sulfide shell, wherein the zinc sulfide shell externally wraps the copper-gallium-sulfur quantum-dot core; a chemical molecular formula of the core is CuxGa1.33-0.33xS2; the diameter of the core is 2nm to 10nm; the shell thickness of the zinc sulfide shell is 0.3nm to 3nm. The method comprises the following steps of firstly mixing a copper source, a gallium source and a sulfur source, then putting in an inert atmosphere, heating, carrying out heat preservation, raising a temperature, reacting to obtain a CuGaS quantum-dot reaction solution, afterwards, injecting a zinc precursor solution into the CuGaS quantum-dot reaction solution, carrying out the heat preservation, then adding n-hexane and ethanol into an obtained mixture, agitating to obtain a turbid solution, and carrying out solid-liquid separation treatment on the turbid solution, so that a target product is prepared. A stimulated emission spectrum of the CuGaS-ZnS quantum-dot material reaches the wide wavelength range of 520nm to 620nm; further, the position of a light emission peak of an output spectrum is adjustable; the quantum efficiency of a quantum dot of yellow-green light at a position, which is 550nm of the light emission peak, is up to 75 percent; the CuGaS-ZnS quantum-dot material is enabled to be extremely easily, widely and commercially applied to the fields of photoluminescent devices and electroluminescent devices.