Objective：To investigate the effect of enhanced neutrophil respiratory burst on mucoid Pseudomonas aeruginosa biofilm and alginate，the main in extracellular matrix，in vivo. Methods：A rat model of mucoid Pseudomonas aeruginosa biofilm infection in the airway was established，and the rats were treated with the respiratory burst enhancer PMA（BF-PMA group） or normal saline（con－trol group）. The plate count method was used to measure the number of live bacteria in biofilm；a scanning electron microscope was used to observe the structure of biofilm；the sulfuric acid-carbazole method was used to measure the content of alginate in biofilm；HE staining was used to observe pathological injury of lung tissue；ELISA was used to measure the levels of inflammatory factors. Results：The scanning electron microscope showed that compared with the control group，the BF-PMA group had a significantly more complex structure and significantly greater thickness of the biofilm，as well as a significantly higher number of live bacteria in the biofilm（P=0.000）. The BF-PMA group had a significantly higher level of alginate synthesis in biofilm than the control group（P=0.004）. HE staining showed that compared with the control group，the BF-PMA group had significantly greater pathological changes of lung tissue，a significantly higher degree of inflammatory response in lung tissue，and a significantly higher level of inter－feron gamma（IFN-γ）（P=0.002），as well as a significantly higher ratio of IFN-γ to interleukin-10（P=0.023）. Conclusion：En－hanced neutrophil respiratory burst in vivo may promote the synthesis of alginate，an important substance in the extracellular matrix of mucoid Pseudomonas aeruginosa biofilm，and make it more dif－ficult to eliminate mucoid Pseudomonas aeruginosa biofilm. It is often associated with severe pathological injury and inflam－matory response.