In order to improve the quality of tin-phosphor bronze strips, the horizontal electromagnetic continuous casting technology, i.e. imposing alternating electromagnetic field to the horizontal continuous casting process of tin-phosphor bronze strips was developed. The effect of electromagnetic field on the quality of tin-phosphor bronze strips was studied with electron probe microanalysis (EPMA) and optical microscope. The results showed that when the alternating electromagnetic field with 50 Hz frequency and 18 A current was imposed, the crystal grain of the tin-phosphor bronze strips was obviously refined and the segregation and shrinkage cavity were greatly reduced. The quality of tin-phosphor bronze strips was remarkably improved, so the annealing time was shortened from 7 hours to 5 hours, and the service life of graphite mold was extended from 168 hours to 334 hours.