This study aims to identify the mean alpha coefficients of the Child PTSD Symptom Scale (CPSS-5) and examine the moderator role of trauma type and study location. We included studies using the CPSS-5 and reporting a Cronbach's alpha coefficient. Our analysis of 27 studies (k = 31) revealed a mean alpha coefficient of 0.91 for the CPSS-5. Mean internal consistency scores for trauma type ranged from 0.87 to 0.95. Additionally, studies conducted in North America yielded significantly higher mean alpha scores (M[subscript[alpha]] = 0.94) than international studies (M[subscript[alpha]] = 0.87). The CPSS-5 demonstrated reliable measurements across studies, ranging from good to excellent. Trauma type and location (or version of the CPSS-5) may be related to the reliability scores. Individual study characteristics should be considered, and reliability scores should be calculated for individual studies for the suitability of alpha scores for clinical decision-making.