In this paper, boron films were deposited on W6Mo5Cr4V2 high speed steel (HSS) via ion beam sputtering of boron target and implanted with polyenergetic(50 keV, 30 keV, 10 keV) nitrogen ions. The mechanical properties of the implanted layer were tested by Vicker`s hardness and SKODA wear tester. The microstructure of the implanted layer was analysed by X-ray Photoelectron Spectroscopy (XPS) and Fourier Infrared (IR) spectroscopy. Experimental results showed that the HSS substrate was intensified obviously after the implantation of boron and nitrogen ion. When the nitrogen dose equals to 12.8×1017 ions/cm2, the hardness reaches its highest value, HV1982 and the relative wearability was increased for about ten times under the load of 30N. XPS depth concentration profiles show an interfacial mixing between film and substrate, and compared with monoenergetic ion implantation, polyenergetic ion implanted layer have an even N/B distribution. Combined with XPS and IR analysis results, It can conclude that boron exists in the form of boron nitride and first as a-BN or h-BN, with the depth decreasing, it has a tendency to transform to c-BN.