We theoretically and experimentally study the optical trapping of two different microparticles by a double-tapered optical fiber probe(DOFP) which is fabricated by the interfacial etching method. A SiO₂ microsphere and a yeast, or two SiO₂ microspheres with different diameters, are trapped. We calculate and measure the trapping forces on the two microparticles, discuss the impacts of the geometrical size and refractive index on the trapping forces. Both the theoretical calculation and experimental measurements indicate that...