A specially developed experimental platform to measure the wettability of molten metals on solid substrates under high magnetic fields in combination with the sessile drop method is presented in this work. The desired magnetic field was generated by a superconducting magnet containing a channel with a diameter of 300 mm, in which the main body of the experimental apparatus was installed. The developed setup was used to observe the in situ wetting behavior of a molten metal on a solid substrate and simultaneously record sample images in real time under a high magnetic field during the wetting process. Contact angles were determined by analyzing the recorded images with the help of analytical software. Experiments using a typical molten metal and a solid substrate were conducted. The results revealed that the wettability of the molten metal on the solid substrate was obviously improved under a high external magnetic field.