We study the electrochemical oxidation waves of conjugated polymers by examining photoluminescence (PL) quenching and electrogenerated chemiluminescence (ECL) of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT). Different factors such as the anion concentration, the anion size, the electrochemical potential, and the coreactant concentration are investigated for their effects on the behavior of the oxidation waves. Our results show that the wave speeds of PL quenching or ECL can be increased by increasing the anion concentration, decreasing the anion size, or increasing the electrochemical potentials. In addition, the intensity of ECL can be controlled by the coreactant concentration. The transition from pinned to free ECL waves is also studied when an intermediate coreactant concentration is used. These results provide useful insights for understanding the electrochemical oxidation wave phenomenon.