The invention discloses a metal-sulfur battery based on sulfur-rich transition metal sulfide and a preparation method thereof. The metal-sulfur battery comprises a cathode, an anode and an electrolyte; the anode is metal; the cathode comprises transition metal sulfide; a chemical formula of the transition metal sulfide is MSx, wherein x is more than or equal to 3; M is one or more of vanadium, niobium, titanium, molybdenum, tungsten, iron, cobalt and nickel; the metal is lithium, sodium, potassium, magnesium, aluminum, zinc or iron; the electrolyte is an ester-based electrolyte or an ether-based electrolyte. The metal-sulfur battery based on the sulfur-rich transition metal sulfide and the preparation method thereof, disclosed by the invention, have the benefits that transition metal polysulfide is adopted as a cathode material equivalent to sulfur so as to realize the novel metal-sulfur battery such as a lithium sulfur and sodium sulfur battery system, and further the application potential of the metal-sulfur battery is further improved.