"生命周期研究法" can be translated into English as "life cycle research method" or "life cycle analysis approach" (depending on the specific context and emphasis, with "life cycle analysis" often abbreviated as LCA in relevant fields).
"Life cycle research method" emphasizes the research methodology that covers the entire life cycle of a product, process, or system.
"Life cycle analysis approach" highlights the analytical framework used to assess environmental, economic, or other impacts throughout the life cycle.
In academic or professional contexts, "life cycle assessment (LCA)" is also a commonly used term when referring specifically to environmental impact assessments throughout a product's life cycle, but "life cycle research method" or "life cycle analysis approach" can be more broadly applicable to various research contexts.