Focusing on the problem that most conductive hydrogels based flexible sensors easily get failed in the low-temperature environment, an anti-freezing and stretchable polydopamine-reduced graphene oxide/sodium alginate/polyacrylamide (PDA-rGO/SA/PAM) composite organohydrogel was developed via solvent replacement strategy. The experimental results show that the composite organohydrogel have outstanding anti-freezing property, good mechanical property, and excellent sensing property. In addition, the assembled organohydrogel flexible strain sensor can detect multiple human motions, such as finger bending, wrist bending, facial micro-expression, etc., and has played its role in promoting the development of wearable flexible electronics in the future.