To investigate the temperature and humidity stability of melt-blown polylactide (PLA) electret nonwovens with different crystallinity, PLA nonwovens were annealed at 70 ℃ for different time followed by the corona charging process, and decay experiments were carried out under different temperature and humidity conditions. It was found that the crystallinity of the PLA nonwovens increased from 14.0 to 50.8%, with annealing time increased from 0 to 4 h. Initial surface potential and filtration efficiency of the PLA electret nonwovens increased with increasing crystallinity (from 14.0 to 50.8%), with the maximum increment of 18% in the initial surface potential. Moreover, the temperature and humidity stability of the PLA electret nonwovens was enhanced with increasing crystallinity. As for the temperature stability, when humidity was constant and temperature increased from 30 to 50 ℃, a slight drop in the retention rate of the filtration efficiency was observed (≤ 3%) for the PLA electret nonwovens. Regarding the humidity stability, when temperature was constant and humidity exceeded 50% RH, the retention rate of the filtration efficiency for the PLA electret nonwovens decreased significantly (≥ 6%).