This letter presents a design methodology for single- and dual-band reflective-type 90° linear polarization rotators (PRs) utilizing orthogonally inserted coupling slotlines. Firstly, a reflective second-order PR element is designed by employing two meandered slotlines etched on orthogonal printed circuit boards (PCBs). An accurate equivalent circuit model (ECM) is utilized to analyze the proposed PR element. Secondly, by etching two additional slotlines in the same element, two coupling paths are established. By properly altering the coupling strength and the operation frequencies of the corresponding coupled slotlines, the single- and dual-band PRs can be realized, respectively. Meanwhile, the corresponding ECMs have been investigated to illustrate their operation principles. Finally, two prototypes have been fabricated and measured to verify the simulated results, and good agreements are achieved.