Abstract: Two layers of Co106F, Co112F and Ni55 powders were deposited on the surface of F51 duplex stainless steel by plasma surfacing. The F51 steel after surfacing was studied by metallographic examination, line scanning analysis and hardness test. The results show that there was no obvious difference in the microstructure of Co106F and Co112F surfacing samples, which were composed of dendrites. The microstructure of Ni55 surfacing samples was closely distributed, and disordered columnar crystals appearred at the interface between the first layer and the second layer of surfacing, which was caused by supercooling. The average hardness of the surfacing layer of Co106F, Co112F and Ni55 surfacing samples was 1. 5,1. 6 and 1. 62 times that of the matrix, respectively. The surface hardness of Co106F surfacing sample was the smallest, and the surface hardness of Ni55 surfacing sample was the largest.