Online P2P lending marketplaces match individual lenders and borrowers for unsecured loans via real-time auction without financial institutions as an intermediary. This paper aims to build up a theoretical framework from the perspectives of informational social influence and herding behavior to explain how individual investors’ participation of online financial community influence their credit risk preference in online P2P lending marketplaces under different financial situations. The research proposes that online financial community participants’ credit risk preference is higher than non-participants in investment decision making during non-financial crisis period, whereas online financial community participants’ credit risk preference is lower than non-participants during financial crisis period. This research plans to conduct a field study to test the proposed effect by examining individual investors’ real transaction data on Prosper.com during financial crisis period and non-financial crisis period as well as their membership records on the community of Prospers.org. An analytical model will be further estimated to test the proposition.