A manufacturing method of a LTPS-TFT is provided, including: providing a substrate, sequentially forming a buffer layer, a low temperature poly-silicon layer, a source contact region, a drain contact region, a gate insulator layer, a gate layer, and a dielectric layer on the substrate, respectively forming a first and a second contact holes through the dielectric layer and the gate insulator layer by dry etching to expose the source and the drain contact regions; and on the dielectric layer, forming a source electrode to contact the source contact region through the first contact hole and a drain electrode to contact the drain contact region through the second contact hole. A LTPS-TFT and an array substrate are also provided.