Abstract: ObjectiveTo find out the transmission route of HIV/AIDS cases with unspecified transmission route reported through national network direct reporting system in Henan province. MethodsThe epidemiological survey about the transmission routes of HIV/AIDS cases were conducted. ResultsA total of 726 HIV/AIDS cases with unknown transmission routes were interviewed with the rate of 81.7%, and the transmission routes were found out in 443 cases (61.0%), including 184 sexual transmitted cases (41.6%), 125 cases by blood donation (28.2%), 105 cases by blood transfusion/blood products (23.7%), 16 cases by mother to children transmission (3.6%） and 13 cases by injection drug use (2.9%). ConclusionMore than 60% of the AIDS cases with unknown transmission route can be specified by epidemiological survey, it is necessary to improve the quality of cases reporting and case epidemiological survey.