The work aims to prepare three kinds of Mo-B-Co-Cr composite powder in the method of mechanical milling + cementation and fragmentation, and also MoB-CoCr coating in the method of high velocity oxygen fuel (HVOF). Three kinds of Mo-B-Co-Cr composite powder with mass ratio (m(MoB):m(CoCr)) of 1:1, 2:1 and 3:1 were prepared in the method of mechanical milling+cementation and fragmentation. Microstructure and phases of the powder as-prepared were studied. MoB-CoCr coating was prepared by applying HVOF experiment to Mo-B-Co-Cr composite powder as-prepared with mass ratio of 1:1, and microstructure of the coating was also studied. Microstructure of the composite powder and coating were observed with scanning electron microscope (SEM). Phases of the composite powder was analyzed with X-ray diffractometer (XRD). Mean porosity and thickness of the coating were measured in image method. Each phase in the composite powder bonded well, morphology of the composite powder was subglobular. No impurities or oxidation phenomenon was found in the process of X-ray diffraction. The phases of the (three kinds of) composite powder were mainly Mo, Co and Cr. As the mass ratio of MoB increased, peak value of Mo phase in the composite powder increased gradually. The MoB-CoCr coating prepared by applying HVOF to the composite powder with m(MoB):m(CoCr)=1:1 exhibited typical lamellar structure, and the coating had good compactness, and bonding of all phases in the coating or interface between coating and substrate was good. Subglobular Mo-B-Co-Cr composite powder can be fabricated by ball milling in the method of mechanical milling + cementation and fragmentation, and MoB-CoCr coating with good microstructure can be successfully prepared in HVOF method.