The invention discloses a preparation method of supercapacitor electrode material vanadium sulfide nanoflower. The method comprises the following steps that 1, sodium orthovanadate dodecahydrate and thioacetamide are prepared into a precursor solution, wherein the mass ratio of sodium orthovanadate dodecahydrate to thioacetamide is 1: (1.2-3.5), and the mass concentration of sodium orthovanadate dodecahydrate is 0.02-0.05 g / mL; 2, the precursor solution is subjected to a hydrothermal reaction, a product obtained after the reaction is completed is washed and dried, and the vanadium sulfide nanoflower is obtained. The prepared vanadium sulfide nanoflower is of a three-dimensional structure, stacking of flake vanadium sulfide is well avoided, the specific surface area of vanadium sulfide is increased, the vanadium sulfide nanoflower is used as an electrode material of a supercapacitor, higher specific capacity can be obtained, the circulation service life is prolonged, and high energy density and power density are achieved; the maximum specific capacity of the prepared vanadium sulfide nanoflower can reach 500.4 F g<-1>, after circulation is conducted 500 times or above, the specificcapacity still reaches 459.4 F g<-1>, and the capacitance retention rate is 91.9%.