A manufacturing method of a low temperature poly-silicon (LTPS) array substrate is described. The LTPS array substrate includes a metal light-shielding layer, a buffer layer, a polycrystalline silicon layer, a gate insulating and interlayer insulating layer, a gate line layer, and a source and drain electrode layer. The method adopts a one-time chemical vapor deposition process to form a gate insulator and interlayer insulating layer. A gate line trench is formed in the gate insulating layer and the interlayer insulating layer, thereby reducing the thickness of the LTPS array substrate film layer and the process steps.