Purpose: Crowdsourcing is a process of obtaining needed services, ideas, or products by soliciting contributions from a large group of people, and especially from an online community, rather than from traditional employees or suppliers. It has been popular in E-business supply chain management This paper studies the risk raking behavior in crowd sourcing adoption and tries to find out how the perceived risks of contract-issuing party would influence their consumption behavior. We constructs a theoretical model for perceived risk of contract-issuing party to characterize how perceived risk of contract-issuing party serves the E-commerce transactions and the antecedents of the perceived risk, taking Witkey as a case. The model comprises four concepts of perceived risk, namely perceived financial risk, perceived time risk, perceived services risk, perceived psychosocial risk, which influence the transaction online. We posit the hypothesis that factors of website, such as authenticity, convenience and safety, are assumed to decrease the perceived risk of contract-issuing party, which accordingly influence crowdsoucing adoption.Methodology: The paper tests the hypothesis with the questionnaires on the interaction of Witkey and contract-issuing party. 325 questionnaire responses were collected from contract-issuing party and Witkeys and employees of the Witkey website. Questionnaire response validation and reliability were tested and structural equation modelling was used to analyze the data.Findings: The results show that most of the hypotheses were supported. Specifically, adopting intention was negatively affected by contract-issuing part’s perceived risks had significant effects on satisfaction. Both website authenticity and website convenience had significant negative impact on the four dimensions of contract-issuing part’s perceived risks. Website security had significant negative impact on three of contract-issuing part’s perceived risks (perceived financial risk, perceived time risk and perceived services risk) while only website authenticity was found to have no significant relation to contract-issuing part’s perceived psychosocial risk.Contribution: On the theoretical side, our study extended the perceived risk research on the contract-issuing parts in Witkey mode, i.e. this study added website factors as pre-factors of the contract-issuing part’s perceived risk, and explored the dimensions of contract-issuing part’s perceived risk. It fills a gap in the contract-issuing part perceived risk theory under Witkey mode, and laying a solid foundation for further in-depth study. From a practical perspective, the results of our study provide implications for Witkey websites which want to improve their service quality and enhance their competitive advantage. It is necessary to promote techniques to protect contract-issuing part’s personal information, improve the payment system, and simplify the payment process with signs to remind users, which can decrease contract-issuing part’s perceived risks.