Occupational asthma refers to asthma caused by exposure to asthma-causing substances in the occupational environment. Its incidence is closely related to the level of industrial development. In addition, its incidence is also related to the nature of the asthma-causing substances. For example, among workers who have long-term exposure to the asthma-causing substance isocyanate, the incidence of occupational asthma is about 5% to 10%. Among workers who are engaged in the detergent industry and have long-term exposure to proteolytic enzymes, the incidence is 50% or even higher. With the development of industry, the incidence of occupational asthma in my country is also increasing year by year. Specific bronchial provocation test is the most valuable method for diagnosing occupational asthma and screening occupational asthma-causing substances. Avoiding contact with allergens is the most important measure to treat occupational asthma.