The invention discloses a hydrothermal preparation method for NiS2 with a controllable shape, and the method mainly comprises the following steps of: mixing 
nickel salt, a sulphur source and a complexing agent in a certain 
molar ratio, transferring the mixture into a high-
pressure reactor, adding 
distilled water, and stirring to adequately dissolve 
soluble solids; adjusting the pH value of the 
reaction system, sealing the reactor, and reacting at a certain temperature; and washing the obtained product by use of 
distilled water and 
ethanol respectively, centrifugally separating, and 
drying. The hydrothermal preparation method for NiS2 with a controllable shape disclosed by the invention has the advantages of being simple in operation by using a hydrothermal method, moderate in reaction condition, narrow in 
particle size distribution, high in product purity, easy in industrial production, and the like. The particle shape and size of NiS2 can be controlled by adjusting the synthesis conditions such as 
hydrothermal reaction temperature, reaction time, complexing agent type and pH value, and the prepared NiS2 can be approximately-cube-shaped, spherical, sheet-shaped and the like. Compared with a 
solid-state reaction method, an 
ultrasonic spray pyrolysis method, a gamma-
ray irradiation method and an 
organic solvent hot method, the NiS2 prepared by the hydrothermal method has the advantages of being low in 
reaction temperature and equipment demand, less in 
toxicity on a 
human body, high in safety factor, low in production cost, capable of meeting the requirements of 
energy conservation and emission reduction, and the like.