Abstract: Three ashes containing V and Ni were preparation for the study. CaO addition and coal ash blending were chosen for regulation of high temperature flow properties. The regulation mechanism was explored by XRD, SEM-EDX and ternary phase diagram analysis. The results show that karelianite and Ni are main refractory matters in petroleum coke ash at high temperature. CaO addition and coal ash blending decrease the liquid temperatures of ash components except V and Ni, which reduces the ash fusion temperatures. When the contents of V and Ni are fewer than 30% in ash, CaO can obviously decrease the fusion temperature of ash, and the viscosity-temperature property becomes crystal type. When the contents of V and Ni are higher than 30% in ash, coal ash blending is an effective method to decrease the fusion temperature. In this condition, 5% of coal ash blending ratio is required, and its viscosity-temperature property is suitable for slag tapping, but when the coal ash proportion is 10% the viscosity-temperature property of ash becomes crystal type for the precipitation of vanadium-rich spinel, which cannot meet the requirement of slag tapping.