In recent years, the problems of fossil resources depletion and environmental pollution make an urgent need to sustainable materials. Poly(lactic acid) (PLA) seems to be one of the most suitable materials due to its renewability, comparable mechanical properties to those of traditional synthetic polymers, energy savings, and price reduction. However, PLA is much susceptible to hydrolysis, restricting it being employed in durable applications. With the aim of improving PLA’s durability and thus expanding its applications, our study focuses on the mechanism of hydrolysis of PLA and then the stabilization of PLA during its service life. Here is part of our research results. By investigating the change of residual mass, pH value and moisture absorption of PLA, PLA-coat-PFA (PLA coated with polydodecafluorheptylmethylacrylate (PFA)) and PLA-blend-PFA (PLA blended with PFA), the hydrolysis of the systems were studied, and the results are as follows. (1) The three systems all show significant reduction in mass after the 40 days hydrolysis but the mass loss rate is different from each other, PLA being the fastest while PLA-coat-PFA being the lowest, indicating that the hydrolysis of PLA can be resisted by PFA. (2) The pH of the three systems all decrease continuously with hydrolytic time and PLA-coat-PFA exhibits the highest pH. The pH of PLA-blend-PLA reduces faster than both of the other two systems at the first 40 days, then trends to be similar to PLA. (3) At the first 60 days, PLA-coat-PFA behaves the lowest moisture absorption indicating a water barrier of PFA, and the moisture absorption of PLA-blend-PFA is higher than that of PLA. After 60 days, however, the moisture absorption of PLA-coat-PFA becomes being the highest while that of PLA becomes being the lowest, implying the different hydrolytic mechanism for different systems, which will be analyzed and discussed in detail in our following report by combining the other results of characterization, such as SEM, GPC, DSC and DCA etc.