This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test pattes with NiSi/SiC and NiSi2/SiC structure are formed on N-wells created by N+ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance pc of NiSi contact to n-type 6H-SiC as low as 1.78×1O-6Ωcm2 is achieved after a two-step annealing at 350℃ for 20 min and 950℃ for 3 min in N2. And 3.84×1O-6Ωcm2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N+ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope.