AIM: To explore the clinical features, diagnosis and treatment experience and the distribution characteristics of pathogenic microorganisms of primary canaliculitis, and provide reference for its diagnosis and treatment. METHODS: Retrospective clinical study. A total of 119 cases(120 eyes)diagnosed as primary canaliculitis in the department of ophthalmology of Wuxi No.2 People's Hospital from June 2019 to February 2023 were included. The treatment methods were mainly divided into conservative treatment(removing canaliculus stones through lacrimal punctum combined with injecting antibiotic eye ointment into the tube)and surgical treatment. The inspection methods of pathogenic microorganisms included secretion smear microscopy and microbial culture.RESULTS: Primary canaliculitis was more common in middle-aged and older female, mainly manifested by long-term red eye and increased secretion; however, the majority was not accompanied by tearing. Totally, 118 cases(99.2%)had monocular disease, while 63 cases(63 eyes; 52.5%)had inferior lacrimal canaliculus disease. Laboratory examination: Among 119 cases(120 eyes), 4 cases(4 eyes)did not undergo laboratory examination, and the other 115 cases(116 eyes)were as follows: Gram staining microscopy of secretion smear showed that Actinomyces were detected in 102 cases(103 eyes; 88.8%), while no fungus was detected; Microbial culture: 85 cases(86 eyes; 74.1%)were positive for bacterial culture. A total of 111 bacterial strains were cultured, which contained 26 types of bacteria. Among them, 32 strains were aerobic(28.8%); 26 strains were anaerobic(23.4%); and 53 strains were facultative anaerobic(47.7%). The most common bacteria were streptococcus(20 strains), staphylococcus(13 strains), Propionibacterium(10 strains), and capnocytophaga(10 strains). Only 4 cases(4 eyes; 3.4%)of microbial cultures were positive for Actinomyces. Fungus was negative in all microbial cultures. Treatment: Of the 119 cases(120 eyes), 114 cases(115 eyes; 95.8%)were cured by conservative treatment of removing lacrimal canaliculus stones through lacrimal punctum and intracanalicular ointment infiltration(IOI), while 5 cases(5 eyes)were not effective in conservative treatment; however, all of them were cured after surgical treatment, and the cure rate for primary canaliculitis was 100.0%.CONCLUSION: The incidence of primary canaliculitis is low, and it is prevalent in middle-aged and older female. Single lacrimal canaliculus is more common, which could be missed and misdiagnosed in clinic. Actinomyces is the major pathogen observed mostly in mixed infections, with heterogeneous strains, mainly anaerobic or facultative anaerobic bacteria. Streptococcus and Staphylococcus are the most common whereas fungal canaliculitis is rare. The cure rate of primary canaliculitis is high after diagnosis, and IOI method is recommended as the initial treatment of canaliculitis.