To solve the mechanical damage caused by direct contact when the fiber optic tweezers captures particles, a single fiber long-distance capture method based on photothermal effect is proposed. Mesoscale silica spheres can be moved and trapped freely within 800 μm by utilizing a C-band fiber broadband amplified spontaneous emission source with a power of less than 20 mW. To find out the capture mechanism, COMSOL Multiphysics finite element analysis software is used to simulate the temperature field distribution, convective velocity field distribution, and particle motion trajectories when the fiber is at different heights in the silica suspension. It is shown that the drag force generated by the heat convection plays a crucial role in the process of the manipulation of microparticles, while the capture speed and capture distance can be changed by adjusting the fiber height. The optical fiber microfluidic device has the advantages of simple structure and flexible operation, and can realize large-scale capture of large particles by using low-power lasers.