The invention discloses an acrylic-ester hot-melt pressure-sensitive adhesive and a preparing method thereof. The acrylic-ester hot-melt pressure-sensitive adhesive comprises, by weight, 1-10 parts of hard monomer, 70-95 parts of soft monomer, 1-5 parts of functional monomer, 1-5 parts of polymerizable UV photoinitiator, 0.2-0.5 part of free radical polymerization initiator and 0.01-0.1 part of molecular weight modifier. According to the acrylic-ester hot-melt pressure-sensitive adhesive, storage stability and weather resistance can be improved, the size shrinkage is small during cure crosslinking, coated base material adhesive force is large, adhesive shifting is not prone to occurrence, and the acrylic-ester hot-melt pressure-sensitive adhesive can be widely applied to the food contact field and the medical field. In addition, the body polymerization technology is adopted and is different from the conventional solution polymerization technology and the conventional emulsion polymerization technology, the amount of residual monomer in macromolecule prepolymers is quite small, the content of solid of a polymerization product is 100%, solvent discharging and water volatilization are avoided in the coating process of the pressure-sensitive adhesive, energy consumption is low, and the environment is protected.