A highly energy efficient circuit for an AC ceiling fan motor in high speed gear, which comprises a speed regulator and a ceiling fan motor whose output torque at full voltage exceeds a required torque at rated load. Two ends of a winding of the ceiling fan motor are connected to a voltage-regulating capacitor bank and a zero line, respectively. The voltage-regulating capacitor bank comprises a first capacitor bank for enabling low speed operation of the ceiling fan motor by stepping down by a third capacitor, a second capacitor bank for enabling medium speed operation of the ceiling fan motor by stepping down by a second capacitor and the third capacitor in parallel, and a third capacitor bank for enabling high speed operation of the ceiling fan motor by stepping down by a first capacitor, the second capacitor and the third capacitor in parallel.