In this work, the large AMOLED Display Backplane LTPS 5Mask PA method was studied. A storage cap was formed by doping boron on the poly Si under the GI cap in the contact hole process without using a storage cap doping mask. In the contact hole process, half-tone PR was used to simultaneously perform cap doping and TFT Source drain open. Since half-tone PR must remain uniform to protect the cap lead-in end with GI uniformly within 8 G Glass, photolithography PR process conditions with good half-tone uniformity were set up.