A modularized control circuit of a fan motor is used to provide a phase-sensing control to the fan motor. The modularized control circuit includes a driving circuit and a microcontroller IC. The driving circuit is electrically connected to the fan motor to produce a plurality of analog driving voltage signals to drive the fan motor. The microcontroller IC is connected to the driving circuit and includes a phase-sensing module, a control unit, and a driving signal generator. The phase-sensing module receives the analog driving voltage signals to sense phases thereof and to produce a phase trigger signal. The control unit is connected to the phase-sensing module and receives a speed signal and the phase trigger signal to produce a control signal. The driving signal generator is connected to the control unit and receives the control signal to produce at least one switch driving signal to control the driving circuit.