In software development process, identifying the key risks factors are the important premise for the risk management and project cost and schedule controlled. Based on the analysis of literature study, project interviews and expert consultation, 47 potential risk factors are put forward from requirements, organizational environment, user, technology, personnel, plan and control and market. Then, through questionnaires, factor analysis and regression analysis, 8 factors and 38 risk factors are identified, which constitutes the key risk factors set of software project.