The embodiment of the present invention discloses a touch unit, an array substrate, a liquid crystal cell substrate and a touch display device. The touch unit comprise a plurality of touch sub-units, each of which comprising a sensor thin film transistor (TFT), an sensing capacitor, a reading induction line and a memory capacitor, the capacitance of the memory capacitor being less than that of the sensing capacitor. Due to the memory capacitor is added to stabilize the voltage of the sensor TFT, the interference of noise upon the voltage of the sensor TFT is reduced, thus effectively improving the signal stability of the touch unit.