Abstract: The present study had shown that the detection rate sof Hemoly ticstreptoc occus in indoor air in public places were increased form 44. 2% during non-epidemic period of influen zato 77. 8% during influenza epidemic period, and the detection points of Hemolytic streptoc occus> 36cfu /m³ were in creased from 2.2 time to 11.1 times, especially the points of simly equipped places. In the meantime, some kind of gram-positive bacteria with hemolytic rings was found in company with Hemolyticstrep tococcus. Though the above results were obvious, the bacteria totals in those places were below its standard.The results of ours showed that Hemoly ticstrep tococcusisan indicator which can represent the population pollutionand the epidemic of respiratory system diseases, and the level of Hemolytics treptococcus no more than 36 cfu/m³ is practicableand applicable.