The invention relates to an electro-deposition method of Sn-Bi series lead-free low-temperature solder. The electro-deposition method is characterized by including the processes of preparing a base plating solution and electro-deposition. According to the electro-deposition method of the Sn-Bi series lead-free low-temperature solder, a plating solution with bismuth sulfate, stannous mono-sulphateand silver citrate used as main salts and with sodium citrate as a complexing agent is added with an antioxidant, a buffer agent, a stabilizer and a brightener, the stability of the plating solution is improved, cathodic polarization is increased, the uniformity and brightness of a plating are improved, and thus the physical performance of the alloy solder is improved. Optimized electro-depositionprocess parameters are calculated by training a feedback algorithm, and the alloy solder with the optimal mechanical performance is obtained.