Abstract: Objective The study was conducted to establish the baseline and the alert curve of influenza surveillance according to the conditions in Shenzhen to make scientific and effective earl ywarning of influenza epidemic. Methods The influenza surveillance data in the First People'sHospital of Shenzhen and the Municipal Children and Women Hospital from 2003 to 2006 were collected for the statistical analysis of the percentage of influenza- like cases, ILI (%), on a weekly basis to determine the baseline and alert curve. Results The surveillance results were reliable. Thebaseline value was 5.95%, and the alert curve had good sensitivity and seasonality, being timely infinding unusual value. Conclusion The reference lines of the influenza surveillance in Shenzhen havegood sensitivity and seasonality. They play certain roles in early warning.