With high performance of No.781, the highest sewing speed is 3600rpm ;With the use of computer servo motor and direct-driven way, it can start up sewing rapidly, save resources effectively, and reduce cost, which can saves about 50% when compared with ordinary machine. Thick materials can be sewed easily through strengthening 550V servo motor, even if the penetrating power is strong; without crashes between starting bract and upper wheel, rapid electromagnet draw bar starting mode can lighten labors’ fatigue and improve work efficiency. Control functions of cloth-feed cam with the use of optical inductor, so that adjustment becomes much more simple and convenient. Mechanical wear is avoided through programming of electric cabinet.