: Tin-lead solder alloy has been used for soldering for many years. Its application has been limited in recent years due to the toxicity of lead. For this reason, researches are trying to find lead-free solders with similar properties to tin-lead solder. Tin-zinc eutectic alloy is one of these alloys that has a reasonable price and low melting point. However, due to problems such as low oxidation resistance and poor wetting ability, it has limited use. In present study, to make lead-free solder, tin-zinc eutectic alloy was first prepared by vacuum smelting. Microstructural studies and differential calorimetry were performed to evaluate alloying and to achieve optimal manufacturing conditions. According to the obtained results, it was found that alloying was performed by holding the melt under vacuum for 90 minutes at a temperature of 500°C. Then, in the second step, the lead-free Sn-9Zn matrix nanocomposite solder reinforced with polymer nanofibers was manufactured by angular accumulative extrusion method. The results showed that performing 10 passes of accumulative extrusion process with 80% reduction of cross section in each pass, causes the optimal distribution of nanofibers in the matrix. Tensile strength, shear strength, electrical resistance, microhardness, X-ray diffraction and X-ray energy diffraction spectroscopy tests were performed for characterization. Addition of 0.1 and 0.3 wt.% of nanofibers increased the final tensile strength by 30 and 40% and improved the wettability by at least 20% compared to the monolithic sample. However, adding 0.5 wt.% of polymer nanofibers caused a decrease in some properties of the nanocomposite compared to the monolithic sample. Microhardness and shear strength for samples containing 0.1, 0.3 and 0.5 wt.% of nanofibers increased by 23, 25, 20 and 36, 49 and 26%, respectively. In order to evaluate the performance of the synthesized solder during application, the microstructure and mechanical properties of the solder after re-melting were investigated. According to the studies, the process of angular accumulative extrusion caused a proper distribution of nanofibers in the matrix. On the other hand, it was found that polymer nanofibers can improve the properties of tin-zinc lead-free solder. Keywords: Tin-zinc eutectic alloy, lead-free solder, nanocomposite, microstructure, mechanical properties, angular accumulative extrusion