Abstract: In order to improve the corrosion resistance of the NiTi alloy, the surface of NiTi alloy was alloyed with Nb by the double-glow plasma alloying technology, and a 28 μm thick alloyed layer was generated on the surface. Field emission scanning electron microscopy and EDS spectroscopy were used to test the morphological characteristics and composition of the Nb alloyed layer, and X-ray diffractometer was used to analyze the phase composition of the alloy layer. An electrochemical workstation was used to test the polarization and impedance spectral curves to analyze the corrosion resistance of the surface. The results show that compared with those of the NiTi alloy, the hardness of the Nb alloying layer sample increases from (202.18±5.67) HV0.3 to (432.74±25.41) HV0.3, the self-corrosion potential is positively shifted from -0.3096 V to -0.2211 V; the self-corrosion current density decreases from 4.93×10^-7 A·cm^-2 to 9.15×10^-8 A·cm^-2. The Nyquist diagram shows that the impedance arc of the alloyed layer sample is bigger than that of the substrate, and the contact resistance R_p of the alloying layer increases from 8.19 Ω·cm^-2 to 19.22 Ω·cm^-2, and the charge transfer resistance R₁ increases from 4.26×10⁵ Ω·cm^-2 to 1.80×10⁶ Ω·cm^-2, and the corrosion resistance is improved.