Traditional　pneumatic　soft　actuators　have　been　widely　used　in　the　field　of　soft　robotics　owing　to　their　high　output　force　and　large　deformation　capabilities.　However,　their　bulky　pumping　systems　pose　limitations　on　their　portability　and　miniaturization.　In　this　study,　we　propose　a　method　of　PVA　film-assisted　manufacturing　chamber　and　design　an　electrothermal　soft　actuator　based　on　a　phase　change　material.　The　actuator　makes　the　phase　change　material　filled　in　the　chamber　change　into　the　vapor　phase　by　heating　from　the　embedded　electrothermal　wire,　thus　driving　the　actuator　to　deform.　The　actuator　designed　in　this　article　can　achieve　a　unilateral　deformation　of　17　mm　and　an　output　force　of　0.265　N　at　a　voltage　of　5　V　(the　weight　of　the　actuator　itself　is　1.5　g).　In　addition,　based　on　the　absolute　node　coordinate　method,　we　adopt　the　hyperelastic　material　model,　which　can　well　describe　the　large　deformation　behavior　of　this　soft　structure,　to　model　the　actuator.