Abstract: In the recent years, severe reoccurrence of Porcine Epidemic Diarrhea (PED) has been recorded in China. In the present study, specific PED related symptoms were observed repeatedly up to six times in the same herds. To investigate the possible factors involved in the PEDV persistent infections and repeat outbreaks. Feces, semen and air samples were collected and examined by RT-PCR and quantified by real-time RT-PCR. The results showed that all of the spike gene sequences of samples at different time were highly homologous. PEDV was shed in fecal excretions at high concentration (up to 1x106.85 copies mL-1) and the shedding time lasted for at least 56 days under field condition. Semen collected from boars without PED clinical phenomena and air samples were positive for PEDV RNA as well.