Abstract: Objective To evaluate the performance of internet-based reporting of HIV/AIDS in China in 2009 and provide scientific evidence to improve reporting quality and establish indicators for management and evaluation. Methods The data and related reporting tables of HIV/AIDS were collected from national AIDS internet-based reporting system on 1 January 2010 to conduct analysis on accuracy, completeness and timeliness of case reporting. The evaluation and verification of AIDS prevention data were implemented in three stages of self evaluation at county level, provincial evaluation and national evaluation with the indicators of the qualified rate of reporting tables and rate of internet-based reporting. Results Of the case reported in 2009, 63.3％ were reported by CDCs at all levels of which 68.9％were reported by CDCs at county level. The errors in report card filling were found in some cases. In some cards, the identification card number, telephone number and working unit were missed. Transmission route item was filled in all report cards, but 9.5% of them were filled with uncertain. Epidemiological surveys were conducted for 98.4％of the cases and the data obtained were entered into the internet-based reporting. The survey was completed for 90.9％of the cases. Up to 88.8％of the cases were reported within 15 days after confirmation or diagnosis by Western blotting. The qualified rate of report cards and rate of internet-based reporting were 94.3％ and 99.3％ respectively at provincial level, and the qualified rate of report cards and rate of internet-based report were 98.9％and 100.0％ respectively at national level. Conclusion The timeliness of case reporting and rate of epidemiological survey in 2009 were much higher than those in 2006, 2007 and 2008. The evaluation indicated that the quality of data reporting was good, but it is still necessary to improve the internet-based reporting of HIV/AIDS.