The invention relates to a system and a technology for recovering sodium nitrate from tin-containing waste liquid treatment tail water. The system for recovering sodium nitrate from tin-containing waste liquid treatment tail water comprises a waste water storage pool, a purification refining device, a multi-effect evaporator, a filter, a crystallization device, a centrifugal machine and a drying machine. The technology for recovering sodium nitrate from tin-containing waste liquid treatment tail water comprises the following steps of collecting tin-containing waste liquid treatment tail water, storing the collected tin-containing waste liquid treatment tail water in the waste water storage pool, feeding the tin-containing waste liquid treatment tail water in the waste water storage pool into the purification refining device to carry out purification refining, feeding the tin-containing waste liquid treatment tail water subjected to purification refining into the multi-effect evaporator, feeding steam into the multi-effect evaporator to carry out circulation evaporation, feeding the steam obtained by the previous step into the filter to carry out heat filtration, feeding the filtrate into the crystallization device to carry out crystallization to obtain crystals, carrying out centrifugation of the obtained crystals by the centrifugal machine to obtain solid slag and a mother solution, transferring the solid slag to the drying machine to carry out drying to obtain a sodium nitrate finished product, and feeding the mother solution back to the waste water storage pool for recycle. The system for recovering sodium nitrate from tin-containing waste liquid treatment tail water has the advantages of relatively low recovery cost, simple and convenient operation management, long-term and stable operation and no discharge of pollutants.