IntroductionIt remains unknown whether psychological or psychosocial treatments for post-traumatic stress disorder (PTSD) have comparable effects across the life span. This study aims at comparing the effects of psychological/psychosocial treatments for PTSD between different age groups of youth, early-middle adults and late adults.Methods and analysisA systematic search will be conducted among thirteen electronic databases, including Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PsycINFO, EMBASE, ERIC, PubMed, SCOPUS, Web of Science, Published International Literature on Traumatic Stress, China National Knowledge Infrastructure Database, the Wanfang database, the Chinese Scientific Journal Database (VIP Database) and ProQuest Dissertations and Theses, from inception to 15 May 2022. Electronic searches will be supplemented by a comprehensive grey literature search in Conference proceedings and trial registries. Randomised controlled trials (RCTs) comparing psychological or psychosocial treatments for PTSD with control conditions in all age groups will be included. The primary outcome is the between-treatments efficacy for PTSD that refers to the outcomes of the RCTs included in the meta-analysis. Effect sizes will be calculated for all comparisons and pooled with a fixed effects model or a random effects model. Differences in the efficacy of psychological/psychosocial therapies for PTSD across the age groups will be examined by stratified analyses and meta-regression analyses.Ethics and disseminationData used in this study will be anonymised. These data will not be used for other purposes than research. Authors who supply the data will be acknowledged. The authors declare that no conflicts of interest exist. The findings of this study will be disseminated through briefing reports, publications and presentations.Trial registration numberCRD42022334305.