The development of a modified method to produce heat treated twisted nanofibrous yarns using two oppositely metallic spinnerets system is presented. This method allows the production of more uniform, stronger twisted poly acrylonitrile (PAN) yarns. The novelty of this system permits for in-situ heat treating of the nanofiber yams. The average diameter of twisted nanofiber yams is 340.65 mu m with 5.8 CV%. The values of the initial modulus and stress of heat treated yams increase from 1.90 GPa and 61.30 MPa in untreated one to 4.51 GPa and 116.56 MPa, respectively. In order to quantify the alignment of the nanofibers Fourier power spectrum (FPS) and image analysis were used. So the treated yam shows more degree of nanofiber alignments than the untreated one.