During the course of this study, rosin-PEG derivatives were successfully synthesized from natural China rosin and PEG using ZnO 2% as a catalyst, with a 2:1 molar ratio of rosin: PEG at 250°C for 9 hours. The obtained water-soluble rosins were completely soluble in water; the derivative of rosin-PEG3000 showed the highest melting point at 55.2°C. Water-soluble solid fluxes were the target for this study; therefore, a derivative of rosin-PEG 3000 was chosen for the investigation of water soluble rosin fluxes characteristic. The study revealed that succinic acid, glutaric acid, ethylammonium chloride, and diethylammonium bromide showed higher wetting ability and were chosen for the production of fluxes. WSRFs were prepared and characterized, with WSRF 09 and WSRF 04 being the best water-soluble fluxes with good solder-ability, low halide content (less than 1500 ppm), high insulation resistance, and low corrosion even though “no-clean” conditions were adopted. Soldering performance was high using lead-free solder Sn-0.7Cu. The flux characteristics complied with type AA according to JIS Z 3283. Therefore, this water-soluble material is more attractive as a water-soluble flux vehicle for electronic industrial materials due to the reduction of use of petroleum-based polymers and the overall cleanliness of water.