Abstract: Objective This study was conducted to analyze the factors affecting the quality of data from direct network reporting on infectious diseases. Methods Infectious diseases reporting cards, reported by different kinds of medical institutions from January to December of 2006 in Taiyuan, were obtained from the Disease Surveillance Data Report and Management System, and then exported in Excel format. Statistical analysis was done on the timeliness, integrity and accuracy of the infectious disease reporting cards reported from medical institutions of different levels and by different reporting methods. Results The major problems of the quality of direct network reporting on infectious diseases in Taiyuan included delayed reporting and lack of completeness and timeliness. Of the reported diseases, hepatitis B, pulmonary tuberculosis and bacillary dysentery were the main types that influenced the quality of reporting. The examination of the reports were often delayed on statutory holidays. Conclusion Measures should be taken as soon as possible to reduce the factors impacting infectious disease reporting.