We present the facile modulation of the optical properties of the conjugated polymers via polymer reactions. The polymers composed of diketonate and fluorene were prepared, and boron complexation was performed after polymer synthesis. By changing feed ratios of BF3 center dot Et2O, which is a reagent to produce a boron diketonate complex, the series of polymers with various complexation ratios with boron at the diketonate unit can be obtained. These synthesized polymers showed diverse optical properties. In the solution states, the quantum yields of emission were greatly changed by the complexation ratios with boron. Accordingly, the polymers with complexation ratio of 21% present the largest intensity. In addition, the emission color can be tuned by changing the complexation ratios in the films. From blue to orange, the emissions were achieved. It was revealed that induced charge transfer between fluorene and boron diketonate should be the main path for the emission of the synthesized polymers.