A driving method for an in-cell touch display and a mobile device using the same are provided. The driving method for an in-cell touch display comprises the steps of: dividing a frame period into N display/touch detection sub-periods each comprising a display sub-period and a touch detection sub-period; dividing scan lines into M scan-line sets, wherein a position of each of the scan-line sets corresponds to at least one of touch sensors; supplying a display common voltage to the touch sensor corresponding to the Ith scan-line set when the scan line being scanned in the display sub-period of the Kth display/touch detection sub-period comprises the scan line of the Ith scan-line set, wherein N, M, K and I are natural numbers, K is smaller than or equal to N, and I is smaller than or equal to M.