The work aims to improve the anti-cavitation and erosion resistance of ZG06Cr13Ni4Mo martensitic stainless steel commonly used in hydraulic machinery. The Stellite 6 coating was prepared on the ZG06Cr13Ni4Mo martensitic stainless steel substrate using ultra-high-speed laser cladding. X-ray diffractometer (XRD) was used to analyze the coating phase, scanning electron microscope (SEM), the energy dispersive spectrometer (EDS) to study the structural characteristics of the coating, the HV-1000 microhardness tester to test the coating hardness distribution, and the ultrasonic vibration cavitation test equipment to study the anti-cavitation of the coating, as well as the erosion resistance of the coating studied by the jet erosion wear tester and the cavitation and erosion morphology of the sample surface analyzed by SEM. An Stellite 6 coating with a thickness of about 400 μm was prepared and mainly composed of the γ-Co dendritic solid solution with FCC structure and the Cr23C6 eutectic carbide. The coating was dense, and its contents of Co and Cr were 55.6wt.% and 27.6wt.% respectively, which perfectly retain the chemical composition of the powder. The microhardness of Stellite 6 coating was 570HV0.1, 2.3 times that of stainless steel, and the depth of the heat-affected zone (HAZ) was only 70 μm. The weight loss increased linearly with test duration increased, after 24-hour ultrasonic vibration cavitation test, the weight loss of the coating was 1.1 mg, and 8.0 mg for that of stainless steel. After the 30° erosion test for 180 s, the weight loss of the Stellite 6 coating and the stainless steel were 9.1 mg and 13.5 mg, respectively. Thus, the Stellite 6 coating prepared by ultra-high-speed laser cladding retains the chemical composition of the Stellite 6 powder and with a dense structure, low dilution rate and a narrow heat-affected zone. Besides, the high hardness coating significantly improves the cavitation and erosion resistance of the ZG06Cr13Ni4Mo martensitic stainless steel commonly used in hydraulic machinery.