<p>The rapid advancements in microelectronics technology and artificial intelligence has driven the high integration, miniaturization, and multifunctional capacity of electronic devices, with additional requirements for higher performance. The exploitation of organic dielectric substrates with both low dielectric constant and dielectric loss are crucial to ensuring signal transmission speed and reliability. Polyphenylene oxide (PPO) has been widely used in the field of high-frequency and high-speed substrates due to its excellent dielectric properties, thermal stability, and low moisture absorption. However, there is a lack of comprehensive reviews and discussion on the modification and properties of PPO. The summary of research on PPO-based composites is of great significance for its application. In this review, we discuss the recent advancements in PPO-based composite. Firstly, the structural characteristics and performance advantages of PPO are presented. Secondly, the general modification strategies for PPO are summarized along with recent research literature, including general strategies for chemical modification and physical blending. Further, the performance of PPO-based composites applied to microwave substrates is discussed. Finally, the challenges and opportunities facing PPO-based composites in the future are discussed according to the current development status, which has guiding significance for the application of PPO in electronic information materials and other fields.</p> Graphical Abstract <p></p>