Filamentary keratitis (FK) is a chronic and recurrent disorder of the cornea. FK is reportedly associated with various kinds of ocular surface diseases or conditions. Until now, there have been lacks of studies based on quantitative sample analysis concerning FK incidence regularity and inducement characteristics at different ages. This was a retrospective study of 147 patients (162 eyes) with FK who had been continuously and completely recorded from August 2012 to August 2015 at the Second Affiliated Hospital of Zhejiang University in Hangzhou, east of China. Our results suggest that the causative factors of FK varied at different ages and the distribution of filaments on the corneal surface was also diverse with different inducements.By exploring the frequency and clinical features of FK, we believe that the findings from our research will be clinically significant and aid in the early prevention and treatment guidance of the disease.