A pixel driving circuit and driving method thereof, an array substrate and a display device. The pixel driving circuit can maintain a voltage difference between two terminals of a storage capacitor (Cst) when a gate line scanning is ended. The pixel driving circuit comprises a pixel thin film transistor (T0) and a storage capacitor (Cst), wherein a gate of the pixel thin film transistor (T0) is connected to a gate line, a first terminal of the pixel thin film transistor (T0) is connected to a data signal (Data), a second terminal of the pixel thin film transistor (T0) is connected to a first terminal of the storage capacitor and a second terminal of the storage capacitor (Cst) is grounded. The pixel driving circuit further comprises a follow module connected the first terminal of the storage capacitor (Cst), and configured to maintain a voltage difference between two terminals of the storage capacitor (Cst) when a gate scanning signal (Gate(n)) makes a transition from a high level to a low level, so as to enable the pixel electrode to obtain sufficient voltage thereby ensuring the display effect of the liquid crystal display.