P2P ( peer-to-peer) online lending refers to the micro credit loans between persons or between per-sons and small firms in the world，which is conducted on the network lending platforms． As a new internet fi-nance service，P2P online lending becomes not only a business focus，but also an academic research frontier． This paper reviews the literature on P2P online lending from three aspects: The influencing factors，herding effect，and social network of lending transactions． Because China has surpassed USA to be the largest P2P on-line lending market，some promising future researches are proposed considering the specific situations and sce-narios in China．