The invention relates to a contact angle measuring device through a high-temperature pendant-drop method. The contact angle measuring device comprises a high-temperature electric furnace which is disposed under a high-temperature molten block furnace. The high-temperature electric furnace is connected with the high-temperature molten block furnace through a thermal insulation interlayer. A silicon carbide rod is arranged in the high-temperature molten block furnace, a corundum tube is disposed inside the silicon carbide rod, a molten material is contained in the corundum tube, an outlet is formed in the bottom of the corundum tube, and a corundum rod capable of blocking the outlet is arranged in the corundum tube. The thermal insulation interlayer is provided with an opening, an opening is formed in the position, below the opening of the thermal insulation interlayer, of the high-temperature electric furnace, a silicon molybdenum rod is disposed in the high-temperature electric furnace, a sample piece support is mounted inside the silicon molybdenum rod, and sample sheet steel is put on the sample piece support. The outlet of the corundum tube, the opening of the thermal insulation interlayer, the opening of the high-temperature electric furnace and the sample sheet steel are maintained on the same perpendicular line, the high-temperature electric furnace is further provided with a fire observing opening, the outside of the fire observing opening directly faces a CCD camera, and the CCD camera is connected with a computer. The process of deposition of molten ash particles on the heated surface in a power station boiler is simulated, and the problem of slag-bonding of the heated surface is studied through real-time records of the contact angle.