The present invention relates to a process for producing a non-oriented silicon steel sheet having a low watt loss and an improved magnetic flux density. Generally, increasing the content of silicon and aluminum in a steel reduces the watt loss of the final product but deteriorates the magnetic flux density. Also, increasing the finishing temperature of a steel sheet or to increase the size of the crystal grains of the final product reduces the watt loss of the final product but also decreases the magnetic flux density.In accordance with the present invention, a grade S7 or grade S8 non-oriented electromagnetic steel sheet exhibiting such excellent magnetic properties at a high magnetic field that the magnetic flux density B.sub.50 is 1.67 tesla or more, the watt loss W.sub.15/50 is 2.70 W/kg or less (0.50 mm thick), and the watt loss W.sub.15/50 is 2.20 W/kg or less (0.35 mm thick) is produced by subjecting a high aluminum electromagnetic steel containing not less than 2.5% silicon and not less than 1.0% aluminum to cold-rolling at a high reduction ratio before finishing-annealing and by subjecting the cold-rolled steel sheet or strip to finishing-annealing at a high temperature of 1050.degree. C. or more for a very short period of from 3 to less than 60 seconds.