Disease prevention has three levels of prevention principles: primary prevention: also known as etiological prevention, the fundamental elimination and control of occupational disease hazards, and thus prevent the occurrence of occupational diseases. Specific measures are: 1. Technical measures: non-toxic substances instead of toxic substances, use of remote operation or automated or semi-automated operation, and prevention of harmful substances from running, smoking, dripping and leaking. In addition, there are measures to strengthen ventilation, dust removal and detoxification; 2, organizational measures: through reasonable organization and arrangement of the labor process, the establishment of a sound labor system, and the implementation of the health standards set by the state; 3, health care measures: do a good job of pre-employment medical examination, to early detection of susceptible persons and occupational contraindications, do a good job of health promotion, health education, pay attention to a balanced diet and the supply of health food. In addition, to strengthen exercise, improve the body’s resistance; secondary prevention: also known as preclinical prevention, through early detection, early diagnosis, early treatment, to prevent the development of disease damage. Firstly, regular health check-ups, clear diagnosis and timely treatment will be carried out for people with occupational exposure. Secondly, the environment of production will be monitored regularly, and prevention and control measures will be taken immediately when problems are detected. Tertiary prevention: also known as clinical prevention, i.e. patients will receive timely and reasonable treatment after clear diagnosis to prevent disease deterioration and recurrence, and thus prevent loss of labor capacity. In addition, patients with chronic occupational diseases will be treated through medical supervision, prevention of complications and disability, mainly through functional and psychological rehabilitation, so that they can be sick but not disabled, disabled but not invalid, and eventually achieve the purpose of prolonging their lives.