Abstract: Objective This study was to find out the status of water contamination caused by legionellae in hospitals and probe into corresponding prevention and control measures．Methods Water samples from air condition cooling tower，secondary ware supply and drinking water supply system in 12 randomly selected hospitals were collected and tested for legionellae．Results 22 out of 48 water samples from air condition cooling tower were positive for legionellae (45.83％)，2 out of 22 water samples from secondary water supply system were positive (9.09％).No legionellae was found in samples from drinking water supply system．Conclusion The air condition cooling tower and secondary water supply system in hospitals were contaminated by legionellae．Corresponding preventive and control measures should be formulated to prevent legionnaires' disease outbreak．