The invention discloses an array substrate. The array substrate has a display region and a non-display region; the non-display region comprises a flexible substrate, a lower sub metal routing line formed on the flexible substrate, a first planarization layer which covers the lower sub metal routing line, and an upper sub metal routing line which is formed on the first planarization layer and electrically connected with a third metal layer in the display region; and the upper sub metal routing line is in electrical contact with the lower sub metal routing line by running through the via hole ofthe first planarization layer to form a peripheral metal routing line. According to the array substrate, the upper sub metal routing line is in electrical contact with the lower sub metal routing line through the via hole to form the peripheral metal routing line; and the height difference between the third metal layer and the upper sub metal routing line is low or even equal to zero, so that a fracture layer is not generated easily between the display region and the non-display region, and the display region and the non-display region can be in effective metal connection, thereby improving the yield of the display screen. The invention also provides a preparation method of the array substrate and a display screen.