Abstract: In order to control the shape and distribution of hard phase in surfacing deposit, longitudinal DC magnetic field was applied to the plasma arc surfacing of two iron-based alloys (Fe5 and Fe3). Hardness, wearing, microstructures and X-ray diffraction of the two surfacing deposit were tested. So the structure and property of the two powders' surfacing deposit were studied. The results show that the surfacing deposit of introducing magnetic field has higher hardness and better wearing resistance than the surfacing deposit without magnetic field; The properties of surfacing deposit are optimal when magnetic field current is 3A; The ideal hard phases such as Cr7C3, CrB etc are obtained and solid solutions of α and γ are refined sufficiently.