Objective To investigate a case of imported dengue fever in Jiangbei New District of Nanjing, China, and to conduct vector mosquito surveillance and control response for testing and harmonizing the dengue prevention and control measures. Methods According to the requirements in the technical guidelines for the prevention and treatment of dengue fever issued by Chinese Center for Disease Control and Prevention, emergency surveillance and epidemiological investigation were performed for an imported dengue case in June 2018. Results A case of imported dengue fever from Cambodia was confirmed by quantitative real-time PCR. Breteau index (BI) and the double mosquito net method were used to monitor the density of mosquito vectors. From June 15 to July 2, the BI in the core area decreased from 3.24 to 0.44, and the net trap index decreased from 6.00 to 0.75 mosquitoes/(net·h). BI<5 and the net trap index <2 were observed in the warning area. No new cases were found during follow-up. Conclusion Epidemic management was given in a timely manner, and vector surveillance and control were fully implemented. No secondary cases were observed.