BACKGROUND: Timely monitoring HIV epidemic among key populations is a formidable challenge. This study aimed to evaluate the agreement between data collected from an enhanced HIV sentinel surveillance (HSS+) and an HIV service, and to discuss whether testing service data can be used for surveillance purposes. METHODS: The HSS+ data were collected from HIV sentinel surveillance conducted annually among men who have sex with men (MSM) between 2009 and 2013 in Guangzhou, China. The HIV service data were obtained from the China-Bill & Melinda Gates Foundation Cooperation Program on HIV Prevention and Care (China-Gates HIV Program) in Guangzhou during the same period. The China-Gates HIV Program aimed to increase HIV counseling and testing among MSM. We compared demographic characteristics, condom use, HIV testing history, and the HIV status among individuals in these two datasets. The Armitage-trend test was used to evaluate the HIV epidemic and behaviors of the participants in the two datasets over the study period. RESULTS: Overall, a total of 2224 and 5311 MSM were included in the surveillance and service datasets, respectively. The majority of participants in the two datasets were between 20 and 29 years old, at least attended college, and had never been married. However, socio-demographic characteristics varied slightly between the two datasets. Similar trends were observed for the HIV epidemic in these two datasets. The surveillance dataset indicated that HIV prevalence increased from 3.9% in 2009 to 11.4% in 2013 (P-value for trend < 0.001), while data from the HIV service dataset indicated that MSM HIV prevalence during this same period increased from 6.2 to 8.9% (P-value for trend = 0.025). The rates of condom use were similar between the two datasets and remained consistent throughout the study period. CONCLUSION: HIV service data can complement existing HIV surveillance systems for MSM in China, though it may underestimate the HIV prevalence (HSS+ data contains people whose status is already know, while service data contains people who were initially negative or people of unknown status). HIV service data can be used for surveillance purposes, when prerequisite variables are collected from a large number people, if the quality assessment is conducted.