Abstract: The flow characteristics of coal ash is one of the important factors affecting liquid slag discharge. To en⁃ sure the smooth process of liquid slag discharge，it is necessary to fully understand the melting and flow characteristics of relevant ash at high temperature. The main purpose of this study is to develop a visual measurement method for the high temperature flow characteristics of coal ash，to understand more about the flow characteristics of experimental coal ash.In the visualization measurement method proposed in this paper，the CCD camera was used to moni⁃ tor the whole flow process of the Jianger coal ash，Tacheng coal ash and Zhundong coal ash in real time，and the flow length and flow velocity of each coal ash sample were obtained by using MATLAB and other image processing software. The cinder sample was adhered to the corundum sheet after heat treatment in advance，and then the experiment was carried out in the form of inverted flow. In the experiment，the contact of substrate was reduced by the flow of ash sample，and the flow resistance was optimized. In addition，various morphological parameters of ash could be obtained by image processing，and the high-temperature flow characteristics could be comprehensively considered by combi⁃ ning multiple parameters. To verify the reliability of the experimental results，the FactSage software was used to calcu⁃ late the viscosity of coal ash at different temperatures，and the calculated results were compared with the experimental results.The results show that the Jianger coal has the worst fluidity among the three kinds of coal ash，while the fluidi⁃ ties of the other two kinds of coal ash are closer.The characteristic viscosity temperature and flow characteristic temper⁃ ature of each sample were obtained. The characteristic viscosity temperature T25 of Jianger coal，Tacheng coal and Zhundong coal samples were 1 324，1 302，1 298 °C respectively，while the critical flow temperature TC of the three coals were 1 299，1 282，1 279 °C respectively.The above characteristic temperature results can provide some ref⁃ erence information for the work in related fields.Mineral analysis shows that the sintering process of coal ash forms blue marble with low melting point，and the melting of blue marble promotes the flow of coal ash to a certain extent， while the formation of high melting point magnesium minerals (magnesia anorthoxite，magnesia spinel，etc.) inhib⁃ its the flow of coal ash.In general，by comparing the flow experiment and viscosity calculation results，the measurement results of the visual measurement method are in good agreement with the viscosity results，which confirms the effective⁃ ness of the method.