The invention relates to an electronic commutation control system of a variable-capacitance electrostatic motor. The electronic commutation control system comprises a rotation speed / rotation angle detecting unit, a micro controller and an output amplifying unit. The invention also provides an electronic commutation control method of a variable-capacitance electrostatic motor. The method includes the following steps that: S1, driving voltage is applied, and a rotor starts rotating at a ti time point, and the rotation speed / rotation angle detecting unit is utilized to only provide one path of rotation speed signals of the rotor; S2, the micro controller is utilized to capture the rising edge of the rotation speed signals of the rotor, and a time point at this moment is recorded as ti+1, and a rotation speed signal cycle Ti can be expressed by the equation that Ti=t(i+1)-ti, wherein i is an integer, and a rotation speed coefficient ks is set to belongs to (0, 1], and ks*Ti / 3 is set to be pulse width required by driving voltage at a next cycle; S3, the output amplifying unit is utilized to output three-phase driving voltage signals; and S4, S2 and S3 are repeated, and therefore, high-speed synchronous rotation of the rotor can be realized.