The formation opportunities of university spinoff companies lie in the knowledge creation. However, the complexity and diversity of knowledge would result in two different knowledge overflow channels, the internal commercialization and the technology transformation to industry through screening or filtering in the commercialization decisionmaking process. This research considers internal commercialization as the formation opportunities of university spinoff companies and measures the influence of knowledge characteristics on such formation opportunities. University resource endowments and policy supports are set as moderating variables. The results from positive test show that the decisive elements of USOs’ formation opportunities are the innovativeness and the market coupling degree of knowledge characteristics. It also indicates that USOs’ formation depends on the university resource endowments and policy supports play certain moderating effects in this process.