Abstract: To investigate the effect of spinning solvents on coaxial electrospun nanofibers and prepare thermal regulation nanofibers, polyethylene glycol (PEG) and polylactic acid (PLA) solutions were used as inner and outer layer spinning solutions respectively, and PLA/PEG nanofibers (Nf_C-S) were prepared by coaxial electrospinning. Three types of Nf_C-S were prepared using deionized water, tetrahydrofuran (THF), and dimethyl carbonate (DMC)/N, N-dimethylformamide (DMF) as inner solvents, named PP_w, PP_t, and PP_d, respectively. The morphology, chemical structure, crystalline properties, mechanical properties, thermal properties, and hydrophilicity of Nf_C-S were studied, and the thermal regulation function was further investigated. The results showed that PP_w obtained fibers with two different scales, and the average diameter increased by 190 nm compared to PP_d. PP_w exhibited higher elastic modulus and breaking stress, while PP_d and PP_t showed higher breaking strain, with the breaking stress of PP_w increasing by 0.54 MPa compared to PP_t. Nf_C-S possessed the melting endothermic capacity attributed to PEG, with PP_t and PP_w exhibiting significant temperature hysteresis during heating and cooling processes, demonstrating excellent thermal regulation capability. The hydrophobicity of Nf_C-S was lower compared to pure PLA (PP₀), with the water contact angle of PP_w (136.5°) being closest to PP₀. In conclusion, thermal regulation Nf_C-S was developed based on the research for inner layer solvent, with PP_w showing superior comprehensive performance, providing a reference for the controllable preparation of thermal regulation nanofibers.