Abstract: Objective The study was conducted to develop an influenza warning system according to the current conditions in Shenzhen so that influenza outbreaks and subsequent socioeconomic loss could be minimized. Methods Alert curves of influenza like illness (ILI), curves of influenza virus isolation and plots of ILI outbreaks from January to August, 2007 in Shenzhen were analyzed to assess the changing trends of influenza epidemic based on the three level warning indicators. Results Consistency between ILI surveillance, isolation of virus and outbreaks of ILI was observed with peaks in late June. The three level warning system was therefore practically feasible. Conclusion The three level influenza warning system proved to be sensitive and practical for preventive prediction of influenza cases in Shenzhen.