Bionic skin sensors based on conductive polymer gels have garnered interest for their potential applications in human-computer interaction, soft robotics, biomedical systems, sports, and healthcare, because of their intrinsic flexibility and stretchability embedded atthematerial level, and other such as self-healing, adhesion, high, and low temperature tolerance properties that can be tuned through macromolecular design. Here, important advances in polymer gel-based flexible sensors over recent years are summarized, from material design, sensor fabrication to system-level applications. This review focuses on there presentative strategies of design and preparing of conductive polymer gels, and adjusting their conductivity, mechanics, and other properties such as self-healing and adhesiveness by controlling the macromolecular network structures. The state-of-art of present flexible pressure and strain sensors, temperature sensors, position sensors, and multifunctional sensors based on capacitance, voltage, and resistance sensing technologies, are also systematically reviewed. Finally, perspectives on issues regarding further advances and challenges are provided.