The invention provides a rotation control system for a tower crane, which comprises a rotation control frequency changer and a sensor mounted on a tower arm, wherein the frequency changer comprises a parameter storage unit, a running state acquisition unit and an output compensation unit; the sensor is used for detecting first running frequency and first acceleration of the position of the sensor in real time; the running state acquisition unit is used for acquiring the first running frequency and the first acceleration from the sensor; the parameter storage unit is used for storing a frequency adjusting coefficient and an acceleration adjusting coefficient; and the output compensation unit is used for adjusting second frequency and second acceleration output to a rotary motor by using the frequency adjusting coefficient and the acceleration adjusting coefficient. The invention further provides a rotation control method for the tower crane. The running data of the tower arm is acquired by the sensor, and the output of the rotation control frequency changer is adjusted according to the acquired running data, so that the influence of a large inertia system of the tower arm of the tower crane on rotation control is gotten rid of from the source.