This thesis carries out detailed technical economical analysis on four make-up water treatment schemes for large-scale boiler with water source of medium and low salt content, namely "total demineralization system," "ultrafiltration plus reverse osmosis plus primary demineralization system plus mix bed," "ultrafiltration plus primary and secondary reverse osmosis plus mix bed" and "ultrafiltration plus primary and secondary reverse osmosis plus electrodeionization." Based on the analysis, the author has come to the conclusion that large-scale boiler make-up water treatment system with water source of medium and low salt content shall select "ultrafiltration plus extra-low pressure reverse osmosis plus primary demineralization system plus mix bed" scheme because of its excellent technical capability and moderate investment and operating expense. If the salt content of raw water exceeds 270mg/L, then "ultrafiltration plus reverse osmosis plus primary demineralization system plus mix bed" treatment scheme with superior technical and economic performance shall be chosen.