Four kinds of electrospun fibrous membranes, random and highly aligned poly (ethylene terephthalate) (PET) fibrous membranes, and random and highly aligned PET/CA (citric acid) fibrous membranes, were prepared by electrospinning technology. The mechanical properties and wetting behavior of the four kinds of electrospun fibrous membranes were studied. Meanwhile, the influence of the thickness of electrospun fibrous membranes on mechanical properties was discussed. Studies have shown that the mechanical properties of aligned PET fibrous membranes are much better than those of random PET fibrous membranes, yet the elongation of aligned PET fibrous membranes are slightly less than that of random PET fibrous membranes. The water contact angle of PET fibrous membranes was decreased from 132.3 degrees to 0 degrees with the addition of citric acid. The wetting behavior of aligned PET/CA fibrous membranes is better than that of random PET/CA fibrous membranes. Meanwhile, the mechanical properties of random PET/CA fibrous membranes dramatically decreased due to the addition of citric acid, yet the mechanical properties of aligned PET/CA fibrous membranes slightly decreased. The elongation of random PET/CA fibrous membranes increased from 284.1% to 444.5%. The mechanical properties of random fibrous membranes improved with increasing the thickness of membranes first and then little decreased. The mechanical properties of aligned fibrous membranes improved with increasing the thickness of membranes.