Abstract: Objective To analyse the influenza-like cases collected via surveillance system from end of 2006 to beginning of 2007,so as to promote methods of adjusting the data deviation in surveillnce system and analyzing the forecasting.Methods According to the 2006~2007 Influenza Surveillance Plan of Beijing,the surveillance data collected from Jan 1,2007 to Jan 14,2007 in the 67 sample hospitals in influenza-like surveillance system was selected,for leverage the adjustment to ILI% in- dicator.Results The results of the first two weeks of 2007 showed:original ILI% in aver age was 6.50%(range from 5.08% to 9.37%),while ILI% adjusted was 10.75%(range from 9.46% to 11.57%)in average,which showed the sensitivity and accuracy of ILI% indicator after adjustment was better.Conclusion The surveillance data collected by the surveillance system was affected by many factors such as government policy,medium and regulations.By closely tracking and analyzing the deviation of surveillance data,as well as efficiently adjusting,the forecasting capability of surveillance system may be improved.