The invention relates to polylactic resin as well as a preparation method and application thereof, and belongs to the technical field of high polymer material synthesis. The intrinsic viscosity of thepolylactic acid resin is 0.95 to 1.55 dl/g, the weight-average molecular weight of the polylactic acid resin is 145000 to 195000, and the polydispersity index of the polylactic acid resin is 1.55 to2.11. The preparation method of the polylactic acid resin comprises the following steps: (1) dissolving lactide in an organic solvent, adding a catalyst, controlling the reaction temperature to be 120-160 DEG C and the reaction pressure to be 20-2000pa, and performing a ring-opening polymerization reaction for 10-25 hours, wherein the organic solvent is C5-C12 aliphatic hydrocarbon or C5-C11 alicyclic hydrocarbon; (2) after the reaction is finished, dissolving the solid obtained in the step (1); and (3) dropwise adding a methanol solvent into the product obtained in the step (2), performing filtering, performing washing with methanol, and performing drying at 60-90 DEG C for 2-6 hours to obtain the polylactic resin. The light transmittance T of the polylactic acid is not lower than 85%, and the haze H is not higher than 35%.