The work aims to improve the oxygen (O2) and water (H2O) barrier properties of poly(L-lactic acid) (PLLA) films and to solve the problems of poor ductility. The melt blending method was used to prepare films by blending poly(butylene adipate terephthalate) (PBAT) and poly(L-lactic acid-itaconic acid butylene diol ester) (P(LA-BI)) with PLLA, respectively. On this basis, an anti-hydrolyzing agent (Z) with dual function of O2 and H2O barrier property was added for further modification. The addition of Z (6 wt%) significantly increased the elongation at break of PLLA/PBAT and PLLA/P(LA-BI) films to 387% and 316%, while maintaining the mechanical strength of the films, and the films exhibited excellent softness and toughness; The oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) of PLLA/P(LA-BI)/Z6 films were 6.4 cm3/(m2.d) and 43.1 g/(m2.d), respectively, which were 54.6% and 61.9% lower than those before the addition of Z6, and the films obtained excellent O2 and H2O barrier properties. The titratable acidity of yogurt in the PLLA/PBAT/Z6 and PLLA/P(LA-BI)/Z6 groups remained within a reasonable range at the 21st day, which achieved the effect of delaying post-acidification during yogurt storage. In the subsequent sensory evaluation, the yogurt with the addition of Z6 packaging received higher scores compared with the PLLA/PBAT and PLLA/ P(LA-BI) groups. The addition of Z6 anti-hydrolyzing agent, which has the dual functions of O2 and H2O barrier properties, to PLLA-based films improves the ductility of the films, enhances the O2 and H2O barrier properties, and at the same time plays a good quality and preservation effect in the yogurt storage process. Thus, PLLA/PBAT/Z6 and PLLA/P(LA-BI)/Z6 films can be promoted for use in place of commercially available non-biodegradable yogurt packaging materials.