The invention discloses a super-hydrophobic nano-
fiber composite membrane for 
membrane distillation and a preparation method thereof. The nano-
fiber composite membrane has a double-layer structure andcomprises a base layer and a 
surface layer which are compounded with each other, wherein the base layer is a nano-
fiber base film and the 
surface layer is a porous super-hydrophobic separation layer.The preparation method comprises the following steps: preparing a base layer by adopting a 
polymer solution electrostatic 
spinning method, and then carrying out 
hot pressing treatment; thermally dissolving a 
polyolefin material in a 
solvent and stirring them evenly, removing a 
solvent-rich phase under an external force of a vacuum-assisted suction 
filtration method, and depositing a 
polymer-richphase on the surface of the base layer; and then, adding a volatile 
polyolefin non-
solvent to construct a nano-fiber 
composite membrane with a porous structure 
skin layer on a 
microscopic scale. The product membrane prepared by the method provided by the invention is efficient and durable, the preparation method is simple and feasible, the defects of high price, low 
porosity, low 
water vapor fluxand easy 
wetting of membrane pores of a traditional 
membrane distillation membrane can be obviously improved, and the large-scale modification of the existing 
membrane distillation membrane can be easily realized.