This paper develops a framework of the evolution of core competence from the legitimacy view. We take Guangdong WENS for example to test and revise the framework. Finally we draw the following conclusions: in Chinese transitional economy, enterprise’s legitimacy choice plays a crucial role in the process of evolution of core competence; legitimacy choice decides strategy reaction directly and influences core competence through strategy reaction; under multiinstitutional pressures, corporate mainly tends to achieve legitimacy through compromising; cooperative spirit is one indispensable part of entrepreneurship, particularly under the situation of institutional defect, corporate oriented by cooperative spirit tends to choose the legitimacy that performs a higher degree of compliance. The paper argues that over the long term, core competence formed on the previous stage will have a very important effect on institutional pressure, entrepreneurship and legitimacy choice on the later stage.