The present paper reported a case of corneal ulcer caused by Lasiodiplodia theobromae. The male patient was 54 years old. His right eye became red and the pain increased for 3 days. Ophthalmic examination showed mixed hyperemia in the bulbar conjunctiva of the right eye. The whole cornea was gray and cloudy, representing an uneven surface like a map. Light white deposition could be seen below the anterior chamber, and the remaining conditions in the eye were not clear. Corneal curettage specimens were taken for fungal fluorescence staining and culture. The cultured strains were identified by morphology and molecular biology. The drug sensitivity of filamentous fungi was tested by E-test. Septahypha can be seen under fluorescent staining of fungi. After incubation for 14 days, conidia could be seen in the conidiophores. The pathogen was identified as Lasiodiplodia theobromae by sequencing. Drug susceptibility result showed that amphotericin B and voriconazole were relatively sensitive.The corneal ulcer was confirmed to be caused by Lasiodiplodia theobromae. The right eye was treated with fluconazole eye drops q2h, and the fluconazole sodium chloride injection was used with 0.4 g qd via intervenous drop infusion. The patient did not get better after 5 days of treatment and asked to be discharged.