Abstract: Aiming at the problems of low precision of speed regulating and inconvenience of zero(adjustment) of analogical controller of electromagnetic speed regulating motor,the paper designed a full-digital controller of electromagnetic speed regulating motor which took AVR single-chip microcomputer as core,introduced structure,hardware and software design of the controller.It also expounded the key point of design of detection circuit of voltage(zero-crossing,) thyristor trigger(circuit) and measurement(circuit) of pulse conversion in details.The controller applied speed measuring with(frequency) and digital(PID algorithm,) and could meet different load.