Objective To know the contamination situation of the centralized air conditioning-ventilating systems in hotels in Shenzhen City, Guangzhou province and to ensure the indoor air quality when the centralized air conditioning-ventilating systems were at working. Methods 22 hotels were selected to determine the total count of bacteria and fungi in internal surface of pipes and air blow, the dust volume of internal surfaces of pipes, inhalable particulate matter(PM10) in air blow, and Legionellae in cooling tower water. Results The eligibility percent of dust volume, the total number of bacteria and fungi in internal surface was 94.76 %, 95.71% and 91.90 % respectively,the eligibility percent of PM10, the total count of bacteria and fungi in air blow was 42.54%, 94.76% and 84.29% respectively, and the detected rate of Legionellae was 57.50%. Conclusion The pollution in some degrees has been observed in the centralized air conditioning-ventilating systems in hotels of Shenzhen City, so it is considered as the important measure to improve indoor air quality and ensure people health to strengthen management of centralized air conditioning-ventilating systems in the usage.