In order to solve the problem of poor structural stability between micro-nano optical fibers, we use CO2 laser as the heating source to heat two micro-nano optical fibers together, and observe the fusion under the microscope, in the end, we weld two micro-nano optical fibers into one, and the surface of the fiber at the fusion point is smooth, the diameter is uniform. Through the method of CO2 laser heating, the perfect fusion of micro-nano optical fibers is realized, which increases the mechanical stability between micro-nano optical fibers, make it easier to fabricate nano photonic devices.