With the recent endorsement of PrEP by the Chinese government, research is urgently needed to better understand factors impacting PrEP uptake among gay, bisexual, and other men who have sex with men (GBMSM) in China. This study examined willingness to use PrEP for HIV prevention among GBMSM in China through structural equation modeling. We examined the relationship among PrEP-related attitudes, subjective norms, PrEP-related knowledge and beliefs about medicines and willingness to use PrEP. The analysis showed a good fit between the data and both the measurement model (RMSEA = 0.060) and structural model (RMSEA = 0.054). Knowledge, attitudes, and subjective norms were significantly related to intention to use PrEP, whereas the effect of general beliefs about medicines was insignificant. These effect mechanisms point to the importance of designing interventions to support PrEP uptake that target knowledge, enhance positive attitudes about PrEP within social networks, and build positive social norms around PrEP among sexually active GBMSM.