To reduce long-term and excessive mid-span deflections of long-span PC rigid frame bridges, a method of adding precast RPC (reactive powder concrete) columns into the bottom plate of the negative moment region and the mid-span roof of the rigid frame bridge to form RPC-NC (Normal Concrete) composite section was proposed. The RPC-NC composite column was analyzed to investigate the influence of RPC on reducing creep and shrinkage effects of the composite column and the stress redistribution between RPC and NC as well as the mechanical capability of shear bond. Based on the above research, design scheme of prefabricated RPC column used in actual bridge was put forward, and then the influence of the precast RPC column on the whole bridge stress and the mid-span deflection was analyzed by finite element method. The results demonstrate that the added precast RPC obviously reduces the rotation of the negative moment region and the compression stress of NC near RPC, which decreases the long-term mid-span deflection after the construction of the rigid frame bridge by 53.9%.