In the clinical evidence-based decision-making process, factors including benefits and harms, evidence certainty, cost and feasibility of interventions should be considered based on the best evidence. The development of decision threshold of effect size (DTES) for patient health outcomes can help stakeholders understand the benefits and harms of interventions, assess evidence certainty, and interpret research results. Based on international experience, the MERGE Working Group through group discussions, semi-structured interviews, expert consensus, and pilot application developed a set of 8-step guidelines for the development of DTES for health outcomes. These steps included necessity assessment, formation of working groups, selection of patient important outcomes, creation of scenarios based on the best evidence, design of expert consultation questionnaires, analysis of expert consultation results, face-to-face expert consensus, dissemination of the application and reevaluation. The DTES guideline development is intended to provide methodological guidance for stakeholders to develop DTES for health outcome indicators in different domains.