PLLA/CA mixtures of different compositions were successfully electrospun to obtain composite nanofibrous membranes. The microstructures of the membrances changed from homogeneous to heterogeneous with the addition of CA, which was observed by FE-ESEM. The PLLA/CA fabric membranes were characterized by mechanical testing, DSC and contact angle measurements. The tensile stress of the composite fibrous membranes increased obviously with the increase of CA content. DSC results indicated that the CA component was the main factor for the changes of enthalpies in the composite fibers. Contact angle measurements showed the hydrophilicity of the electrospun nanofiber membranes was improved with the addition of CA.