Spirobifluorene (SPF)-based soluble copolymers containing different chain lengths of alkoxy-benzene units in the main chain were synthesized via a chemical oxidative method using FeCl3 as the catalyst. The copolymers are soluble in common organic solvents such as methylene chloride, tetrahydrofuran (THF), and chloroform. The chemical structure and luminescence properties of the as-prepared copolymers were investigated by Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance spectroscopy (1HNMR), ultraviolet-visible (UV-Vis) spectroscopy, and photoluminescence (PL) spectroscopy. With dimethylsulfoxide (DMSO) as solvent, the copolymers emit a strong blue light. The absorption and PL emission peaks appear at 356 and 413 nm, respectively. Using quinine sulfate as the reference, the fluorescence quantum yields of the copolymers were found to be 0.69 and 0.77. Cyclic voltammetry (CV) tests indicated that the highest occupied molecular orbital (HOMO) energy levels of the copolymers are located between -5.85 and -5.69 eV.