The ever-increasing penetration of projects necessitates effective management of multiple projects. Project portfolio management (PPM) is one of the modern project management tools that is utilized for strategy implementation in project-based organizations. This technique includes the following processes: Identification, categorization, evaluation, selection, prioritization, portfolio balancing, and authorization. In this paper, strategy implementation is considered the main goal of the organization. In other words, the more the strategy implementation, the more organizational success. Also, we know that one of the key risk objectives of PPM is detecting inappropriate projects. This ensures that the mix of ongoing projects will be the best available project opportunities. In other words, the importance of selection is enormous. In this paper, first, the main efficiency factors are analyzed and presented new definitions and methods to assess each of them. Based on the literature, four main evaluation factors of a portfolio are: 1) strategy fit, 2) single project success, 3) portfolio balance, and 4) interdependence between projects. Then, a framework is presented based on project strategy and Diamond approach concepts. The framework helps the organization to project evaluation and selection accurately. It also can be used for project prioritization. Some instances such as project definition, project objectives and project success criteria are defined in project strategy. Diamond approach is also used to analyze a project in four dimensions: 1) Novelty, 2) Technology, 3) Complexity, and 4) Pace (NTCP). Key words: Project portfolio management, project selection, strategy, project strategy, risk.