The invention discloses an acrylate pressure sensitive adhesive emulsion of a PET substrate for battery packaging, a preparation method and application thereof. The pressure sensitive adhesive emulsion comprises the following components by weight: 75-85 parts of an acrylate soft monomer, 15-25 parts of an acrylate hard monomer, 2-5 parts of a functional monomer, 1-3 parts of an internal crosslinking monomer, 0.5-2 parts of an anionic emulsifier, 0.5-1 part of a non-ionic emulsifier, 0.1-0.3 part of a buffering agent, 0.02-0.1 part of a defoaming agent, 0.02-0.08 part of a wetting agent, 0.02-2parts of an initiator, 120 parts of water, 0.02-0.1 part of an oxidant, 0.04-0.1 part of a reducing agent, and 1-3 parts of a pH regulator. The pressure sensitive adhesive emulsion provided by the invention has good mechanical properties, can reduce the warping and cracking probability of the PET substrate and ensure the adhesive durability, and is green, low-carbon and environment-friendly.