The successful implementation of software projects is the desire of every software project developer, but according to the data from Standish Group in 2018, the success of developing software projects is still very small at 23%. Therefore, this study conducted action research on ABC Ltd., which has a core business in developing software projects. In developing ABC project there were still projects that have failed such as exceeding the predetermined time target. This research determines the priorities of critical success factors (CSF) that ABC Ltd. must consider in improving the project development process. The data were collected using questionnaires with a pairwise comparison scale and the research respondents were ABC Ltd. employees who were directly involved in developing projects were then analyzed using the Analytic Hierarchy Process (AHP). Based on the results of the analysis obtained clear project goal is alternatives with the highest rank then followed by communication, project planning, clear team composition, top management support, appropriate resource allocation, changes in project requirements, project funding, team competency, project work methodology and project time. Based on the ratings that were obtained, interviews were conducted to obtain stakeholder responses that will become as recommendations in making improvements to each of the success factors of the project, hoping that it could increase the success of software project development at ABC, Ltd.