Thermal flying height control (TFC) has recently been implemented in magnetic recording disk drives to reduce the flying height at the read/write element of magnetic recording sliders. This study numerically investigates the use of AC current to control the temperature and protrusion of the TFC slider. It simulates the eddy current induced by alternating current (AC) applied to TFC heater and its effects on the flying performance of the TFC slider. The results show that the eddy current can be obviously excited in low shield when applying alternating current at the TFC heater. In the investigated TFC slider, the effects of eddy current on temperature rise and thermal protrusion are small. Moreover, the increase in frequency and amplitude of the input alternating current will increase the temperature and thermal protrusion of the slider along with the reduction in flying height. The current amplitude is more efficient than the current frequency to increase the temperature of the slider. Furthermore, the control of frequency and amplitude of alternating current applied to the heater would be necessary to achieve a stable flying height during read/write operation of the TFC slider.