An in-cell multi-touch panel system includes: an in-cell touch display panel, a touch display control system. In a first frame time interval, the touch display control system drives the in-cell touch display panel and samples the sensing voltage from the in-cell touch display panel to determine whether there is an approaching external object and noise interference. In a second frame time interval, the touch display control system finds out a frequency with minimum noise for use as a frequency of the touch driving signal when the noise interference exists. In a third frame time interval, the touch display control system is based on the frequency with minimum noise to correspondingly generate the touch driving signal so as to determine whether there is an approaching external object.