Abstract: Shape memory alloy (SMA) electrothermal actuators are useful in aerospace wings and minimal invasive surgeries because of their high flexibility and high force-to-weight ratio. We designed a sheathcore-structured SMA composite actuator with micro-nano heat dissipation channels constructed on the SMA surface to increase the cooling rate of large SMA electrothermal actuators. The function of the channels is to rapidly transfer heat radially from the SMA to boron nitride nanosheets (BNNS) with a high heat dissipation coefficient through high thermally conductive carbon nanotubes. The composite actuator fabricated herein using a commercial SMA exhibits an increase in operating frequency by one order of magnitude, 50% reduction in cooling time required for reply, 33% stroke, and output force of 70 MPa, realized fast-cycling and were prepared for use in several applications.