For improving HgCdTe MS contacts,the influence of thermal annealing on metal contact on short and middle-wavelength HgCdTe is investigated in this paper.The contact specific resistivity ρc was measured by the transmission line method（TLM）.For short wavelength,p-HgCdTe-Sn/Au contact is obviously a Schottky junction,but the mean contact specific resistivity decreases about 2 order of magnitude after 95 ℃,30 min annealing;and 125 ℃, 30 min annealing would make the mean contact specific resistivity decrease about 3 order of magnitude.n-HgCdTe-Sn/Au contact is an Ohmic contact without annealing.For the middle wavelength,the mean specific resistivity of P-HgCdTe-Sn/Au contact is about 10-1 Ωcm2 magnitude before annealing.A three order of magnitude decrease in specific resistivity has been observed after 70 ℃,125 ℃ and 155 ℃ annealing with different times,furthermore,it is found that Sn/Au is more suitable than Cr/Au to be HgCdTe MS contact metal.So the HgCdTe MS contact can be improved by thermal annealing.