The phase change nanofibers are prepared via electro spinning with the poly(styrene-co-acrylonitrile) (SAN) as carriers and the lauric acid (LA) as the phase change materials (PCMs). The content of the solution, the solubilizer palmitic acid (PA) and the parameters of the electro spinning vary with the favorable conditions of electro spinning. Research has been conducted: the analysis of intermolecular forces between SAN and LA by the infra-red spectra; the examination of the densities of SAN and LA, the voltage and distance of the electro spinning, and the impact of the solubilizers exerting on the form of the phase change nanofibers by SEM; the research on the thermal storage and the crystal structure of the nanofibers by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and the observance of the melting and crystallization of the nanofibers with the polarized optical microscopy (POM). Conclusions are reached as follows: first, the intermolecular forces do exist between the SAN and LA because the blending is physical; second, the nanofibers have moderate temperature, enthalpy of phase transition and good ability to store thermal energy; in addition, the crystal structure of the nanofibers, compared with that of LA, experiences changes. Moreover, it is because the leakage of LA doesn't happen in SAN during the phase transition that the crystal of the nanofibers can remain solid.