Abstract: Since flexible strain sensors require high sensitivity and a wide strain range in healthcare, soft robotics and human-computer interaction, this work designed a flexible strain sensor based on silver nanoparticles-polydopamine-carbon nanotubes (AgNPs-PDA-CNT) sensitive material system, and prepared a layer coated sandwich structure flexible strain sensor. The results of material characterization and property test showed that AgNPs were uniformly dispersed and fixed on the surface of PDA-CNT by virtue of PDA adhesion and reducibility. The AgNPs-PDA-CNT conductive material is closely bonded to the inner wall of silicone rubber capillary tube and polydimethylsiloxane (PDMS). AgNPs-PDA-CNT penetrates into PDMS and the concentration is in gradient distribution. The sensor has high sensitivity coefficient (GF) and wide strain range (69.04 when 0%-44%, 253.13 when 44%-66%, 1253.8 when 66%-76%), fast response (75 ms) and recovery (90 ms), good stability and repeatability. The sensor is applied to human motion monitoring, soft finger ontology sensing and soft grasping behavior monitoring, and good application results are achieved.