Spherical optical microcavities with different diameters (50~250 μm) are fabricated using polystyrene (PS), and they are coupled to tapered fibers. Absorption spectra of the spherical optical microcavities in wavelength range of 1570~1576 nm are measured. Experimental results show that whispering gallery mode (WGM)-based optical resonation occurs in the microcavities in this wavelength range. The wavelength interval between the adjacent resonating modes decreases with the increase of the PS sphere diameters. Quality factors of the PS spheres at the eigen frequencies are calculated according to the absorption spectra, and the results show that values of the quality factors are higher than 104.