A laser-heated cavity system includes: a first cavity provided with a first top end part and a first bottom end part that are arranged opposite each other; wherein the first top end part is provided with a first widow and the first bottom end part is provided with an opening; a second cavity disposed inside the first cavity, provided with a second top end part and a second bottom end part that are arranged opposite each other, and disposed with a second window and a sample bearer; a laser heating assembly disposed outside the first cavity; wherein at least one laser beam provided by the laser heating assembly is passed through the first and second windows, and then focused on the sample bearer; and a mobile platform assembly. The first cavity is a vacuum cavity, and the pressure in the second cavity ranges from vacuum to 30 atm.