This article investigated an occupational chronic benzene poisoning incident that occurred in a sealing material factory in Hebei Province in September 2019, analyzed the clinical data of workers, to explore the causes of occupational chronic benzene poisoning, and summarize the diagnosis and treatment characteristics and treatment outcome. According to GBZ 68-2013 "Diagnosis of Occupational Benzene Poisoning", a total of 12 cases of occupational chronic benzene poisoning were diagnosed among the 20 workers, including 2 cases of occupational chronic mild benzene poisoning, 7 cases of moderate benzene poisoning, and 3 cases of severe benzene poisoning. Both mild and moderate poisoning patients had recovered after treatment. Severely poisoned patients had recovered more slowly, and the white blood cell count was still 2.0×10⁹-3.0×10⁹/L during the 1-year follow-up. This benzene poisoning incident was caused by illegal operations. The responsibility of the employer, the supervision of the administrative agency, and the awareness of personal protection of employees should be strengthened to avoid or reduce the occurrence of poisoning incidents and ensure the health of workers.