The invention provides an acrylate emulsion pressure-sensitive adhesive with a high solid content and low viscosity, and a preparation method thereof. The provided polyacrylate emulsion is prepared by synthesizing 2-ethylhexyl acrylate, butyl acrylate, vinyl acetate, methyl methacrylate, acrylic acid, 2-hydroxypropyl acrylate, vinyl acetate, carboxyl-containing functional monomers, and inter-crosslinked polyacrylate monomers through a pre-emulsifying semi-continuous polymerization technology. Compared to the prior, the provided adhesive has the characteristics of high solid content, which is not less than 65%, and low viscosity, which is less than 800 mPas at a temperature of 25 DEG C under a rotation speed of 60 rpm. The gel content of the adhesive is low, and the stability of the adhesive is good. The adhesive basically does not contain any nonyl phenol or contains very little nonyl phenol, is an environment-friendly acrylate emulsion pressure-sensitive adhesive, and can be used as a single-component pressure sensitive adhesive.