The invention provides photovoltaic welding strip alloy solder and a preparation method thereof. The raw material of the photovoltaic welding strip alloy solder comprises tin-lead alloy, bismuth, indium, phosphorus, cerium, neodymium and germanium. According to the photovoltaic welding strip alloy solder, the bismuth, indium, neodymium, cerium, germanium, gallium, phosphorus and copper are added into the tin-lead alloy, the melting point of the photovoltaic welding strip alloy solder is effectively reduced, the oxidation resistance, welding tension, expansion rate and fluidity of the photovoltaic welding strip alloy solder are improved, and the generation of slag soil is reduced. According to the photovoltaic welding strip alloy solder, the yield of tin products is improved, the productivity of hot tinning products is improved, the wettability of tin plating solution is improved, and other physical and mechanical properties of tin plating products are not affected; and the preparationmethod is simple, the cost is low, the daily maintenance and curing of an existing equipment are not affected, the environmental protection requirements are met, and the working environment of the production site is not affected.