Abstract: Phase-change materials (PCMs) have attracted significant attention in integrated photonics due to their high optical contrast and non-volatile states. However, existing phase-change optical switches based on conventional PCMs suffer from large footprints and high insertion losses, limiting their application in photonic integrated circuits. Here, the optical FOM is adopted as the screening metric for phase-change materials in this work. A compact phase-change optical switching device with low insertion loss is proposed by integrating a novel nitrogen-doped antimony selenide (N-Sb₂Se₃) phase-change material with a high optical FOM into a DC structure. The finite-difference time-domain method is used to systematically investigate the effects of three PCMs on key performance metrics of phase-change optical switching devices, including coupling length, insertion loss, and extinction ratio. Compared with conventional germanium-antimony-tellurium (GST) and antimony selenide (Sb₂Se₃) phase-change materials, N-Sb₂Se₃ exhibits a higher optical FOM in the communication band. Favorable switching performance is achieved for the designed device with a coupling length of 13 µm. In the wavelength range of 1555–1575 nm, the maximum insertion loss of the device is below 0.72 dB, while the port extinction ratio exceeds 7.6 dB. This work provides an effective strategy for the development of low-loss, miniaturized phase-change optical switch devices.