Abstract: Objective To evaluate the quality of national internet-based reporting of notifiable communicable diseases in China from 2005 to 2008 and provide evidence to improve the reporting quality. Methods The data of national notifiable communicable disease surveillance between 2005 and 2008 were collected to conduct the quality evaluation with the different indicators. Structured query language (SQL) was used during the data query and analysis. Results The quality of internet-based reporting of notifiable communicable diseases was improved by years from 2005 to 2008. The rate of timely reporting failure, timely verifying failure and repeated reporting was 3.04%, 0.64% and 0.01% respectively in 2008, which declined by 89.76%, 92.90% and 91.67% respectively compared with 2005. The reporting quality in the central part of China was improved during this period, but the reporting quality in the western part was poor. The timeliness of disease reporting and data verifying were improved gradually, which was 0.57 d and 43 min respectively in 2008. The rate of reporting completeness reached 94.53%. Conclusion The quality of internet-based reporting of communicable diseases is the basis of the disease control and prevention in China. The quality of the reporting had been improved since 2005, but it is still necessary to conduct supervision and evaluation regularly, provide sufficient operation fund and strengthen staff training for the further improvement, especially in the western part of China.