In order to improve the surface hardness and corrosion resistance of stainless steel, single-pass and multi-pass lap laser cladding coatings of Ni25WC35 alloy powders were fabricated on a 1Cr18Ni9Ti substrate by a 6 kW transverse-flow CO2 laser. The coatings were examined and tested for chemical compositions, microstructure features, phase structures, microhardness, corrosion behaviors and metallographies by the X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM), X-ray Energy Dispersive Analysis (EDAX), microhardness tester, electrochemistry workstation and optical microscopy (OM), respectively. The results show that some new harden phases are formed in the coating which consists of (Fe, Ni) solid solution and some compounds such as WC, W2C, CrNiFeC, FeW3C, Ni2Si, Fe3Ni3B, and these harden phases improve the hardness and corrosion resistance of the substrate effectively. OM observation displays that the microstructure of clad coating is homogeneous, compactness and forms a good metallurgical bonding layer with the substrate. Micro-hardness measurement exhibits that the surface hardness of treated sample is twice as large as that of substrate, and the highest hardness lies in the second pass cladding zone center of a double-pass coating sample and reaches 650HV. The electrochemical corrosion test in 5.0% NaCl saturated solution indicates that the maximum self-corrosion potential (Ecorr) of clad coating sample changes from 630.90 mV to positive direction, and the lowest corrosion current density (Icorr) changes from 2.21 μA·cm-2 to 0.55 μA·cm-2 and decreases by 75.11%. Compared with the substrate, the corrosion resistance of laser cladding sample has been improved significantly, and the single pass cladding sample shows the best corrosion behavior.