Region of interest (ROI) readout is an important technology used in the infrared focal plane array(IRFPA) and image sensor readout integrated circuits to improve the frame rate and reduce the bandwidth, which is realized by the reduced ROI size and the readout data volume. Two ROI readout modes including asynchronous readout and synchronous readout are introduced in this paper. The asynchronous readout mode exhibits poor scalability and the problem of the competitive risk, while the synchronous readout mode occupies pixel area and the ROI switching speed is slow. To solve these problems, this paper proposes a row-column control word architecture based on synchronous readout mode, and a reusable unit circuit is designed to improve the scalability for various array size. The circuits and layout for the proposed architecture are designed, which are verified by circuit simulation. Compared with other architectures, the proposal realizes ROI readout at arbitrary position with minimum size of 1×1. Moreover, problems including the occupying of pixel area and competitive risk are solved, as well as the ROI switching speed.