The invention discloses a method for directly separating nickel from copper by wet processing of low-grade nickel matte. The method includes subjecting the low-grade nickel matte to primary countercurrent leaching by sulfuric acid to obtain primary leaching liquor containing nickel, cobalt and iron and primary leaching residues with main ingredients of copper sulphate and precious metals; subjecting the low-grade nickel matte to secondary countercurrent leaching by the primary leaching liquor to obtain secondary leaching liquor containing nickel, cobalt and iron and secondary leaching residues; precipitating hydrogen sulfide gas produced after two times of leaching and the secondary leaching liquor to obtain iron-containing precipitation liquor and nickel-cobalt sulfide precipitation residues; finally, subjecting the precipitation liquor to high-temperature oxidation, hydrolysis and iron removal. The method has the advantages that the whole technological process makes the nickel and the cobalt directly separated from the precious metals and the copper, so that the drawbacks such as high loss of the cobalt, the nickel and the precious metals, high material circulation rate and highenergy consumption are avoided in a process of bessemerizing the low-grade nickel matte into high-grade nickel matte; the traditional technology of separating the nickel from the copper through high-matte grinding flotation is omitted, so that production energy consumption is reduced, and a recovery rate of the nickel, the copper, the cobalt and the precious metals is increased.