At present, the flexible electronic materials with both good flexibility and conductivity have become a major development trend of electronic materials in the future. Due to their flexibility in construction, controllable mechanical properties and electrical conductivity, the conductive polymer-based hydrogels (CPHs) are expected to become one of the candidate materials in flexible electronics and other fields, and have received extensive attention from researchers. However, the existing CPH systems generally have shortcomings such as low mechanical strength and single function. To this end, the authors attempt to construct a hydrogel using polyaniline (PANI) as the conductive component and polyacrylic acid (PAA) as the flexible component through in-situ polymerization and physical blending. The designed PAA/PANI conductive polymer-based hydrogel enjoys ultra-long stretchability and high strength. It can be used in the flexible strain sensors and pressure sensors to detect the step cycle of the multi-legged robot in real time, and adjust their rhythm during the walking gait, thereby achieving the physical balance. This paper provides a new idea for the application of the CPHs, and especially offers a wealth of theoretical foundation and practical experience for the research on its application to the flexible strain sensors.